From: Francis Dupont <fdupont@isc.org>
Date: Thu, 5 Apr 2018 22:12:52 +0000 (+0200)
Subject: [5374] Checkpoint before regen
X-Git-Tag: trac5458a_base~14^2~12
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b6d4dff8ae26c89ed0d9ed5aa2932b383f75afad;p=thirdparty%2Fkea.git

[5374] Checkpoint before regen
---

diff --git a/doc/guide/classify.xml b/doc/guide/classify.xml
index 1721853f0d..0a1b2baf2a 100644
--- a/doc/guide/classify.xml
+++ b/doc/guide/classify.xml
@@ -759,9 +759,9 @@ concatenation of the strings</entry></row>
     <title>Configuring Classes</title>
       <para>
       A class contains five items: a name, a test expression, option data,
-      option definition and eval on-demand flag.
+      option definition and only-if-required flag.
       The name must exist and must be unique amongst all classes. The test
-      expression, option data and definition, and eval on-demand flag are
+      expression, option data and definition, and only-if-required flag are
       optional.
       </para>
 
@@ -786,21 +786,21 @@ concatenation of the strings</entry></row>
       Usually the test expression is evaluated before subnet selection
       but in some cases it is useful to evaluate it later when the
       subnet, shared-network or pools are known but output option
-      processing not yet done. The eval-on-demand flag, false by default,
-      allows to defer and make only on-demand the evaluation of the
-      test expression.
+      processing not yet done. The only-if-required flag, false by default,
+      allows to perform the evaluation of the test expression only
+      when it was required, i.e. in a required-client-classes list.
       </para>
 
       <para>
-      The eval-client-classes list which is valid for shared-network,
+      The required-client-classes list which is valid for shared-network,
       subnet and pool scope specifies the classes which are evaluated
       in the second pass before output option processing.
       The list is built in the reversed precedence order of option
       data, i.e. an option data in a subnet takes precedence on one
-      in a shared-network but an on-demand class in a subnet is added
+      in a shared-network but required class in a subnet is added
       after one in a shared-network.
-      The mechanism is related to the eval-on-demand flag but it is
-      not required that the flag was set to true.
+      The mechanism is related to the only-if-required flag but it is
+      not mandatory that the flag was set to true.
       </para>
 
       <para>
diff --git a/doc/guide/dhcp4-srv.xml b/doc/guide/dhcp4-srv.xml
index f37f3a69f0..479580e11f 100644
--- a/doc/guide/dhcp4-srv.xml
+++ b/doc/guide/dhcp4-srv.xml
@@ -2095,8 +2095,8 @@ It is merely echoed by the server
       is to assess an incoming packet and assign it to zero or more classes.  The
       second step is to choose a subnet, possibly based on the class information.
       The third step is to assign classes from host reservations.
-      The forth step is to build the list of on-demand classes and perform
-      deferred evaluation for each class of the list.
+      The forth step is to build the list of required classes and perform
+      the evaluation for each class of the list.
       The last step is to assign options, again possibly based on the class
       information.
       </para>
@@ -2248,23 +2248,23 @@ It is merely echoed by the server
         </para>
       </section>
 
-      <section id="dhcp4-on-demand-class">
-        <title>On-demand classification</title>
+      <section id="dhcp4-required-class">
+        <title>Required classification</title>
         <para>
         In some cases it is useful to limit the scope of class.
         Two devices are available to perform evaluation of test
-        expressions so assignment when it returns true only on-demand.
+        expressions so assignment when it was required.
         </para>
 
         <para>
-        The first one is the per-class <command>eval-on-demand</command>
+        The first one is the per-class <command>only-if-required</command>
         flag which is false by default. When it is set to
         <command>true</command> the test expression of the class is not
         evaluated at the reception of a new incoming ticket.
         </para>
 
         <para>
-        The second is the <command>eval-client-classes</command> which
+        The second is the <command>required-client-classes</command> which
         takes a list of class names and is valid in shared-network,
         subnet and pool scope. Classes in these lists are evaluated
         after resource assignment and before output option processing.
@@ -2280,7 +2280,7 @@ It is merely echoed by the server
        {<userinput>
            "name": "Client_foo",
            "test": "'' == ''",
-           "eval-on-demand": true</userinput>
+           "only-if-required": true</userinput>
        },
        ...
     ],
@@ -2288,7 +2288,7 @@ It is merely echoed by the server
         {
             "subnet": "192.0.2.0/24",
             "pools": [ { "pool": "192.0.2.10 - 192.0.2.20" } ],
-            <userinput>"eval-client-classes": [ "Client_foo" ],</userinput>
+            <userinput>"required-client-classes": [ "Client_foo" ],</userinput>
             ...
         },
         ...
diff --git a/doc/guide/dhcp6-srv.xml b/doc/guide/dhcp6-srv.xml
index a9b44ff2f2..ed7e22fa5e 100644
--- a/doc/guide/dhcp6-srv.xml
+++ b/doc/guide/dhcp6-srv.xml
@@ -1955,8 +1955,8 @@ should include options from the isc option space:
       is to assess an incoming packet and assign it to zero or more classes.  The
       second step is to choose a subnet, possibly based on the class information.
       The third step is to assign classes from host reservations.
-      The forth step is to build the list of on-demand classes and perform
-      deferred evaluation for each class of the list.
+      The forth step is to build the list of required classes and perform
+      the evaluation for each class of the list.
       The last step is to assign options again possibly based on the class
       information.
       </para>
@@ -2041,23 +2041,23 @@ should include options from the isc option space:
         </para>
       </section>
 
-      <section id="dhcp6-on-demand-class">
-        <title>On-demand classification</title>
+      <section id="dhcp6-required-class">
+        <title>Required classification</title>
         <para>
         In some cases it is useful to limit the scope of class.
         Two devices are available to perform evaluation of test
-        expressions so assignment when it returns true only on-demand.
+        expressions so assignment when it was required.
         </para>
 
         <para>
-        The first one is the per-class <command>eval-on-demand</command>
+        The first one is the per-class <command>only-if-required</command>
         flag which is false by default. When it is set to
         <command>true</command> the test expression of the class is not
         evaluated at the reception of a new incoming ticket.
         </para>
 
         <para>
-        The second is the <command>eval-client-classes</command> which
+        The second is the <command>required-client-classes</command> which
         takes a list of class names and is valid in shared-network,
         subnet and pool scope. Classes in these lists are evaluated
         after resource assignment and before output option processing.
@@ -2073,7 +2073,7 @@ should include options from the isc option space:
        {<userinput>
            "name": "Client_foo",
            "test": "'' == ''",
-           "eval-on-demand": true</userinput>
+           "only-if-required": true</userinput>
        },
        ...
     ],
@@ -2085,7 +2085,7 @@ should include options from the isc option space:
                      "pool": "2001:db8:1::-2001:db8:1::ffff"
                  }
              ],
-            <userinput>"eval-client-classes": [ "Client_foo" ],</userinput>
+            <userinput>"required-client-classes": [ "Client_foo" ],</userinput>
             ...
         },
         ...
diff --git a/src/bin/dhcp4/dhcp4_lexer.ll b/src/bin/dhcp4/dhcp4_lexer.ll
index 05405a39ff..1e68cde4ce 100644
--- a/src/bin/dhcp4/dhcp4_lexer.ll
+++ b/src/bin/dhcp4/dhcp4_lexer.ll
@@ -795,14 +795,14 @@ ControlCharacterFill            [^"\\]|\\{JSONEscapeSequence}
     }
 }
 
-\"eval-client-classes\" {
+\"required-client-classes\" {
     switch(driver.ctx_) {
     case isc::dhcp::Parser4Context::SUBNET4:
     case isc::dhcp::Parser4Context::POOLS:
     case isc::dhcp::Parser4Context::SHARED_NETWORK:
-        return isc::dhcp::Dhcp4Parser::make_EVAL_CLIENT_CLASSES(driver.loc_);
+        return isc::dhcp::Dhcp4Parser::make_REQUIRED_CLIENT_CLASSES(driver.loc_);
     default:
-        return isc::dhcp::Dhcp4Parser::make_STRING("eval-client-classes", driver.loc_);
+        return isc::dhcp::Dhcp4Parser::make_STRING("required-client-classes", driver.loc_);
     }
 }
 
@@ -827,12 +827,12 @@ ControlCharacterFill            [^"\\]|\\{JSONEscapeSequence}
     }
 }
 
-\"eval-on-demand\" {
+\"only-if-required\" {
     switch(driver.ctx_) {
     case isc::dhcp::Parser4Context::CLIENT_CLASSES:
-        return isc::dhcp::Dhcp4Parser::make_EVAL_ON_DEMAND(driver.loc_);
+        return isc::dhcp::Dhcp4Parser::make_ONLY_IF_REQUIRED(driver.loc_);
     default:
-        return isc::dhcp::Dhcp4Parser::make_STRING("eval-on-demand", driver.loc_);
+        return isc::dhcp::Dhcp4Parser::make_STRING("only-if-required", driver.loc_);
     }
 }
 
diff --git a/src/bin/dhcp4/dhcp4_messages.mes b/src/bin/dhcp4/dhcp4_messages.mes
index ca29b07ccc..3f19967084 100644
--- a/src/bin/dhcp4/dhcp4_messages.mes
+++ b/src/bin/dhcp4/dhcp4_messages.mes
@@ -1,4 +1,4 @@
-# Copyright (C) 2012-2017 Internet Systems Consortium, Inc. ("ISC")
+# Copyright (C) 2012-2018 Internet Systems Consortium, Inc. ("ISC")
 #
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -59,12 +59,12 @@ which cannot be found in the configuration. Either a hook written
 before the classification was added to Kea is used, or class naming is
 inconsistent.
 
-% DHCP4_CLASS_UNKNOWN on-demand class %1 has no definition
-This debug message informs that a class is listed for late evaluation but
+% DHCP4_CLASS_UNDEFINED required class %1 has no definition
+This debug message informs that a class is listed for required evaluation but
 has no definition.
 
-% DHCP4_CLASS_UNTESTABLE on-demand class %1 has no test expression
-This debug message informs that a class was listed for late evaluation but
+% DHCP4_CLASS_UNTESTABLE required class %1 has no test expression
+This debug message informs that a class was listed for required evaluation but
 its definition does not include a test expression to evaluate.
 
 % DHCP4_CLIENTID_IGNORED_FOR_LEASES %1: not using client identifier for lease allocation for subnet %2
diff --git a/src/bin/dhcp4/dhcp4_parser.yy b/src/bin/dhcp4/dhcp4_parser.yy
index 81673e4d09..498bddf91e 100644
--- a/src/bin/dhcp4/dhcp4_parser.yy
+++ b/src/bin/dhcp4/dhcp4_parser.yy
@@ -123,9 +123,9 @@ using namespace std;
   HOST_RESERVATION_IDENTIFIERS "host-reservation-identifiers"
 
   CLIENT_CLASSES "client-classes"
-  EVAL_CLIENT_CLASSES "eval-client-classes"
+  REQUIRED_CLIENT_CLASSES "required-client-classes"
   TEST "test"
-  EVAL_ON_DEMAND "eval-on-demand"
+  ONLY_IF_REQUIRED "only-if-required"
   CLIENT_CLASS "client-class"
 
   RESERVATIONS "reservations"
@@ -911,7 +911,7 @@ subnet4_param: valid_lifetime
              | id
              | rapid_commit
              | client_class
-             | eval_client_classes
+             | required_client_classes
              | reservations
              | reservation_mode
              | relay
@@ -982,9 +982,9 @@ client_class: CLIENT_CLASS {
     ctx.leave();
 };
 
-eval_client_classes: EVAL_CLIENT_CLASSES {
+required_client_classes: REQUIRED_CLIENT_CLASSES {
     ElementPtr c(new ListElement(ctx.loc2pos(@1)));
-    ctx.stack_.back()->set("eval-client-classes", c);
+    ctx.stack_.back()->set("required-client-classes", c);
     ctx.stack_.push_back(c);
     ctx.enter(ctx.NO_KEYWORD);
 } COLON list_strings {
@@ -1061,7 +1061,7 @@ shared_network_param: name
                     | relay
                     | reservation_mode
                     | client_class
-                    | eval_client_classes
+                    | required_client_classes
                     | valid_lifetime
                     | unknown_map_entry
                     ;
@@ -1344,7 +1344,7 @@ pool_params: pool_param
 pool_param: pool_entry
           | option_data_list
           | client_class
-          | eval_client_classes
+          | required_client_classes
           | user_context
           | unknown_map_entry
           ;
@@ -1575,7 +1575,7 @@ not_empty_client_class_params: client_class_param
 
 client_class_param: client_class_name
                   | client_class_test
-                  | eval_on_demand
+                  | only_if_required
                   | option_def_list
                   | option_data_list
                   | next_server
@@ -1594,9 +1594,9 @@ client_class_test: TEST {
     ctx.leave();
 };
 
-eval_on_demand: EVAL_ON_DEMAND COLON BOOLEAN {
+only_if_required: ONLY_IF_REQUIRED COLON BOOLEAN {
     ElementPtr b(new BoolElement($3, ctx.loc2pos(@3)));
-    ctx.stack_.back()->set("eval-on-demand", b);
+    ctx.stack_.back()->set("only-if-required", b);
 };
 
 // --- end of client classes ---------------------------------
diff --git a/src/bin/dhcp4/dhcp4_srv.cc b/src/bin/dhcp4/dhcp4_srv.cc
index 2e3f72bafa..58b547d36d 100644
--- a/src/bin/dhcp4/dhcp4_srv.cc
+++ b/src/bin/dhcp4/dhcp4_srv.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2011-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -2340,8 +2340,8 @@ Dhcpv4Srv::processDiscover(Pkt4Ptr& discover) {
     if (!ex.getResponse()->getYiaddr().isV4Zero()) {
         // Assign reserved classes.
         ex.setReservedClientClasses();
-        // Late classification
-        lateClassify(ex);
+        // Required classification
+        requiredClassify(ex);
 
         buildCfgOptionList(ex);
         appendRequestedOptions(ex);
@@ -2397,8 +2397,8 @@ Dhcpv4Srv::processRequest(Pkt4Ptr& request) {
     if (!ex.getResponse()->getYiaddr().isV4Zero()) {
         // Assign reserved classes.
         ex.setReservedClientClasses();
-        // Late classification
-        lateClassify(ex);
+        // Required classification
+        requiredClassify(ex);
 
         buildCfgOptionList(ex);
         appendRequestedOptions(ex);
@@ -2683,7 +2683,7 @@ Dhcpv4Srv::processInform(Pkt4Ptr& inform) {
     Pkt4Ptr ack = ex.getResponse();
 
     ex.setReservedClientClasses();
-    lateClassify(ex);
+    requiredClassify(ex);
 
     buildCfgOptionList(ex);
     appendRequestedOptions(ex);
@@ -2986,8 +2986,8 @@ void Dhcpv4Srv::classifyPacket(const Pkt4Ptr& pkt) {
         if (!expr_ptr) {
             continue;
         }
-        // Not the right time if on demand
-        if ((*it)->getOnDemand()) {
+        // Not the right time if only when required
+        if ((*it)->getRequired()) {
             continue;
         }
         // Evaluate the expression which can return false (no match),
@@ -3017,8 +3017,8 @@ void Dhcpv4Srv::classifyPacket(const Pkt4Ptr& pkt) {
     }
 }
 
-void Dhcpv4Srv::lateClassify(Dhcpv4Exchange& ex) {
-    // First collect on-demand classes
+void Dhcpv4Srv::requiredClassify(Dhcpv4Exchange& ex) {
+    // First collect required classes
     Pkt4Ptr query = ex.getQuery();
     ClientClasses classes = query->getClasses(true);
     Subnet4Ptr subnet = ex.getContext()->subnet_;
@@ -3028,7 +3028,7 @@ void Dhcpv4Srv::lateClassify(Dhcpv4Exchange& ex) {
         SharedNetwork4Ptr network;
         subnet->getSharedNetwork(network);
         if (network) {
-            const ClientClasses& to_add = network->getOnDemandClasses();
+            const ClientClasses& to_add = network->getRequiredClasses();
             for (ClientClasses::const_iterator cclass = to_add.cbegin();
                  cclass != to_add.cend(); ++cclass) {
                 classes.insert(*cclass);
@@ -3036,7 +3036,7 @@ void Dhcpv4Srv::lateClassify(Dhcpv4Exchange& ex) {
         }
 
         // Followed by the subnet
-        const ClientClasses& to_add = subnet->getOnDemandClasses();
+        const ClientClasses& to_add = subnet->getRequiredClasses();
         for(ClientClasses::const_iterator cclass = to_add.cbegin();
             cclass != to_add.cend(); ++cclass) {
             classes.insert(*cclass);
@@ -3051,7 +3051,7 @@ void Dhcpv4Srv::lateClassify(Dhcpv4Exchange& ex) {
         if (!addr.isV4Zero()) {
             PoolPtr pool = subnet->getPool(Lease::TYPE_V4, addr, false);
             if (pool) {
-                const ClientClasses& to_add = pool->getOnDemandClasses();
+                const ClientClasses& to_add = pool->getRequiredClasses();
                 for (ClientClasses::const_iterator cclass = to_add.cbegin();
                      cclass != to_add.cend(); ++cclass) {
                     classes.insert(*cclass);
@@ -3070,7 +3070,7 @@ void Dhcpv4Srv::lateClassify(Dhcpv4Exchange& ex) {
          cclass != classes.cend(); ++cclass) {
         const ClientClassDefPtr class_def = dict->findClass(*cclass);
         if (!class_def) {
-            LOG_DEBUG(dhcp4_logger, DBG_DHCP4_BASIC, DHCP4_CLASS_UNKNOWN)
+            LOG_DEBUG(dhcp4_logger, DBG_DHCP4_BASIC, DHCP4_CLASS_UNDEFINED)
                 .arg(*cclass);
             continue;
         }
diff --git a/src/bin/dhcp4/dhcp4_srv.h b/src/bin/dhcp4/dhcp4_srv.h
index 536ef263da..2569386d79 100644
--- a/src/bin/dhcp4/dhcp4_srv.h
+++ b/src/bin/dhcp4/dhcp4_srv.h
@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2011-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -803,17 +803,17 @@ protected:
     /// @param pkt packet to be classified
     void classifyPacket(const Pkt4Ptr& pkt);
 
-    /// @brief Assigns incoming packet to zero or more classes (late pass).
+    /// @brief Assigns incoming packet to zero or more classes (required pass).
     ///
-    /// @note This late classification evaluates all classes which
-    /// were marked for this deferred/on-demand pass. Classes are
-    /// collected in the reversed order than output option processing.
+    /// @note This required classification evaluates all classes which
+    /// were marked for required evaluation. Classes are collected so
+    /// evaluated in the reversed order than output option processing.
     ///
-    /// @note The eval-on-demand flag is related because it avoids
+    /// @note The only-if-required flag is related because it avoids
     /// double evaluation (which is not forbidden).
     ///
     /// @param ex The exchange holding needed informations.
-    void lateClassify(Dhcpv4Exchange& ex);
+    void requiredClassify(Dhcpv4Exchange& ex);
 
     /// @brief Perform deferred option unpacking.
     ///
diff --git a/src/bin/dhcp4/tests/classify_unittest.cc b/src/bin/dhcp4/tests/classify_unittest.cc
index 18a2230937..504ed6a577 100644
--- a/src/bin/dhcp4/tests/classify_unittest.cc
+++ b/src/bin/dhcp4/tests/classify_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2016-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2016-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -56,7 +56,7 @@ namespace {
 ///     or member(<last two>), set boot-file-name to pxelinux.0
 ///
 /// - Configuration 3:
-///   - Used for late/on-demand classification
+///   - Used for required classification
 ///   - 1 subnet: 10.0.0.0/24
 ///   - 1 pool: 10.0.0.10-10.0.0.100
 ///   - the following classes defined:
@@ -185,19 +185,19 @@ const char* CONFIGS[] = {
         "{"
         "   \"name\": \"pxe1\","
         "   \"test\": \"option[93].hex == 0x0009\","
-        "   \"eval-on-demand\": true,"
+        "   \"only-if-required\": true,"
         "   \"next-server\": \"1.2.3.4\""
         "},"
         "{"
         "   \"name\": \"pxe2\","
         "   \"test\": \"option[93].hex == 0x0007\","
-        "   \"eval-on-demand\": true,"
+        "   \"only-if-required\": true,"
         "   \"server-hostname\": \"deneb\""
         "},"
         "{"
         "   \"name\": \"pxe3\","
         "   \"test\": \"option[93].hex == 0x0006\","
-        "   \"eval-on-demand\": false,"
+        "   \"only-if-required\": false,"
         "   \"boot-file-name\": \"pxelinux.0\""
         "},"
         "{"
@@ -209,7 +209,7 @@ const char* CONFIGS[] = {
         "    \"subnet\": \"10.0.0.0/24\", "
         "    \"id\": 1,"
         "    \"pools\": [ { \"pool\": \"10.0.0.10-10.0.0.100\" } ],"
-        "    \"eval-client-classes\": [ \"pxe2\" ]"
+        "    \"required-client-classes\": [ \"pxe2\" ]"
         " } ]"
     "}"
 
@@ -566,7 +566,7 @@ TEST_F(ClassifyTest, fixedFieldsInformNoClasses3) {
     testFixedFields(CONFIGS[3], DHCPINFORM, OptionPtr(), "0.0.0.0", "", "");
 }
 
-// Class 'pxe1' is on-demand and not subject to late evaluation
+// Class 'pxe1' is only-if-required and not subject to required evaluation
 TEST_F(ClassifyTest, fixedFieldsDiscoverNextServer3) {
     OptionPtr pxe(new OptionInt<uint16_t>(Option::V4, 93, 0x0009));
 
@@ -584,7 +584,7 @@ TEST_F(ClassifyTest, fixedFieldsInformNextServer3) {
 }
 
 
-// Class pxe2 is on-demand but the subnet requests its late evaluation
+// Class pxe2 is only-if-required but the subnet requires its evaluation
 TEST_F(ClassifyTest, fixedFieldsDiscoverHostname3) {
     OptionPtr pxe(new OptionInt<uint16_t>(Option::V4, 93, 0x0007));
 
@@ -633,7 +633,7 @@ TEST_F(ClassifyTest, fixedFieldsInformFile32) {
     testFixedFields(CONFIGS[3], DHCPINFORM, pxe, "0.0.0.0", "", "ipxe.efi");
 }
 
-// This test checks the precedence order in requested late evaluation.
+// This test checks the precedence order in required evaluation.
 // This order is: shared-network > subnet > pools
 TEST_F(ClassifyTest, precedenceNone) {
     std::string config =
@@ -650,7 +650,7 @@ TEST_F(ClassifyTest, precedenceNone) {
         "    {"
         "       \"name\": \"for-pool\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.1\""
@@ -659,7 +659,7 @@ TEST_F(ClassifyTest, precedenceNone) {
         "    {"
         "       \"name\": \"for-subnet\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.2\""
@@ -668,7 +668,7 @@ TEST_F(ClassifyTest, precedenceNone) {
         "    {"
         "       \"name\": \"for-network\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.3\""
@@ -705,7 +705,7 @@ TEST_F(ClassifyTest, precedenceNone) {
     EXPECT_FALSE(opt);
 }
 
-// This test checks the precedence order in requested late evaluation.
+// This test checks the precedence order in required evaluation.
 // This order is: shared-network > subnet > pools
 TEST_F(ClassifyTest, precedencePool) {
     std::string config =
@@ -722,7 +722,7 @@ TEST_F(ClassifyTest, precedencePool) {
         "    {"
         "       \"name\": \"for-pool\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.1\""
@@ -731,7 +731,7 @@ TEST_F(ClassifyTest, precedencePool) {
         "    {"
         "       \"name\": \"for-subnet\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.2\""
@@ -740,7 +740,7 @@ TEST_F(ClassifyTest, precedencePool) {
         "    {"
         "       \"name\": \"for-network\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.3\""
@@ -754,7 +754,7 @@ TEST_F(ClassifyTest, precedencePool) {
         "        \"id\": 1,"
         "        \"pools\": [ { "
         "            \"pool\": \"10.0.0.10-10.0.0.100\","
-        "            \"eval-client-classes\": [ \"for-pool\" ]"
+        "            \"required-client-classes\": [ \"for-pool\" ]"
         "         } ]"
         "    } ]"
         "} ]"
@@ -784,7 +784,7 @@ TEST_F(ClassifyTest, precedencePool) {
     EXPECT_EQ("10.0.0.1", addrs[0].toText());
 }
 
-// This test checks the precedence order in requested late evaluation.
+// This test checks the precedence order in required evaluation.
 // This order is: shared-network > subnet > pools
 TEST_F(ClassifyTest, precedenceSubnet) {
     std::string config =
@@ -801,7 +801,7 @@ TEST_F(ClassifyTest, precedenceSubnet) {
         "    {"
         "       \"name\": \"for-pool\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.1\""
@@ -810,7 +810,7 @@ TEST_F(ClassifyTest, precedenceSubnet) {
         "    {"
         "       \"name\": \"for-subnet\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.2\""
@@ -819,7 +819,7 @@ TEST_F(ClassifyTest, precedenceSubnet) {
         "    {"
         "       \"name\": \"for-network\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.3\""
@@ -831,10 +831,10 @@ TEST_F(ClassifyTest, precedenceSubnet) {
         "    \"subnet4\": [ { "
         "        \"subnet\": \"10.0.0.0/24\","
         "        \"id\": 1,"
-        "        \"eval-client-classes\": [ \"for-subnet\" ],"
+        "        \"required-client-classes\": [ \"for-subnet\" ],"
         "        \"pools\": [ { "
         "            \"pool\": \"10.0.0.10-10.0.0.100\","
-        "            \"eval-client-classes\": [ \"for-pool\" ]"
+        "            \"required-client-classes\": [ \"for-pool\" ]"
         "         } ]"
         "    } ]"
         "} ]"
@@ -864,7 +864,7 @@ TEST_F(ClassifyTest, precedenceSubnet) {
     EXPECT_EQ("10.0.0.2", addrs[0].toText());
 }
 
-// This test checks the precedence order in requested late evaluation.
+// This test checks the precedence order in required evaluation.
 // This order is: shared-network > subnet > pools
 TEST_F(ClassifyTest, precedenceNetwork) {
     std::string config =
@@ -881,7 +881,7 @@ TEST_F(ClassifyTest, precedenceNetwork) {
         "    {"
         "       \"name\": \"for-pool\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.1\""
@@ -890,7 +890,7 @@ TEST_F(ClassifyTest, precedenceNetwork) {
         "    {"
         "       \"name\": \"for-subnet\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.2\""
@@ -899,7 +899,7 @@ TEST_F(ClassifyTest, precedenceNetwork) {
         "    {"
         "       \"name\": \"for-network\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"domain-name-servers\","
         "           \"data\": \"10.0.0.3\""
@@ -908,14 +908,14 @@ TEST_F(ClassifyTest, precedenceNetwork) {
         "],"
         "\"shared-networks\": [ {"
         "    \"name\": \"frog\","
-        "    \"eval-client-classes\": [ \"for-network\" ],"
+        "    \"required-client-classes\": [ \"for-network\" ],"
         "    \"subnet4\": [ { "
         "        \"subnet\": \"10.0.0.0/24\","
         "        \"id\": 1,"
-        "        \"eval-client-classes\": [ \"for-subnet\" ],"
+        "        \"required-client-classes\": [ \"for-subnet\" ],"
         "        \"pools\": [ { "
         "            \"pool\": \"10.0.0.10-10.0.0.100\","
-        "            \"eval-client-classes\": [ \"for-pool\" ]"
+        "            \"required-client-classes\": [ \"for-pool\" ]"
         "         } ]"
         "    } ]"
         "} ]"
diff --git a/src/bin/dhcp6/dhcp6_lexer.ll b/src/bin/dhcp6/dhcp6_lexer.ll
index a8ab21ed1f..d8c8afd79d 100644
--- a/src/bin/dhcp6/dhcp6_lexer.ll
+++ b/src/bin/dhcp6/dhcp6_lexer.ll
@@ -1047,15 +1047,15 @@ ControlCharacterFill            [^"\\]|\\{JSONEscapeSequence}
     }
 }
 
-\"eval-client-classes\" {
+\"required-client-classes\" {
     switch(driver.ctx_) {
     case isc::dhcp::Parser6Context::SUBNET6:
     case isc::dhcp::Parser6Context::POOLS:
     case isc::dhcp::Parser6Context::PD_POOLS:
     case isc::dhcp::Parser6Context::SHARED_NETWORK:
-        return isc::dhcp::Dhcp6Parser::make_EVAL_CLIENT_CLASSES(driver.loc_);
+        return isc::dhcp::Dhcp6Parser::make_REQUIRED_CLIENT_CLASSES(driver.loc_);
     default:
-        return isc::dhcp::Dhcp6Parser::make_STRING("eval-client-classes", driver.loc_);
+        return isc::dhcp::Dhcp6Parser::make_STRING("required-client-classes", driver.loc_);
     }
 }
 
@@ -1081,12 +1081,12 @@ ControlCharacterFill            [^"\\]|\\{JSONEscapeSequence}
     }
 }
 
-\"eval-on-demand\" {
+\"only-if-required\" {
     switch(driver.ctx_) {
     case isc::dhcp::Parser6Context::CLIENT_CLASSES:
-        return isc::dhcp::Dhcp6Parser::make_EVAL_ON_DEMAND(driver.loc_);
+        return isc::dhcp::Dhcp6Parser::make_ONLY_IF_REQUIRED(driver.loc_);
     default:
-        return isc::dhcp::Dhcp6Parser::make_STRING("eval-on-demand", driver.loc_);
+        return isc::dhcp::Dhcp6Parser::make_STRING("only-if-required", driver.loc_);
     }
 }
 
diff --git a/src/bin/dhcp6/dhcp6_messages.mes b/src/bin/dhcp6/dhcp6_messages.mes
index aececc9b71..d59ad58df5 100644
--- a/src/bin/dhcp6/dhcp6_messages.mes
+++ b/src/bin/dhcp6/dhcp6_messages.mes
@@ -1,4 +1,4 @@
-# Copyright (C) 2012-2017 Internet Systems Consortium, Inc. ("ISC")
+# Copyright (C) 2012-2018 Internet Systems Consortium, Inc. ("ISC")
 #
 # This Source Code Form is subject to the terms of the Mozilla Public
 # License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -66,12 +66,12 @@ which cannot be found in the configuration. Either a hook written
 before the classification was added to Kea is used, or class naming is
 inconsistent.
 
-% DHCP6_CLASS_UNKNOWN on-demand class %1 has no definition
-This debug message informs that a class is listed for late evaluation but
+% DHCP6_CLASS_UNDEFINED required class %1 has no definition
+This debug message informs that a class is listed for required evaluation but
 has no definition.
 
-% DHCP6_CLASS_UNTESTABLE on-demand class %1 has no test expression
-This debug message informs that a class was listed for late evaluation but
+% DHCP6_CLASS_UNTESTABLE required class %1 has no test expression
+This debug message informs that a class was listed for required evaluation but
 its definition does not include a test expression to evaluate.
 
 % DHCP6_COMMAND_RECEIVED received command %1, arguments: %2
diff --git a/src/bin/dhcp6/dhcp6_parser.yy b/src/bin/dhcp6/dhcp6_parser.yy
index 0720846ceb..9bfaa141d5 100644
--- a/src/bin/dhcp6/dhcp6_parser.yy
+++ b/src/bin/dhcp6/dhcp6_parser.yy
@@ -116,9 +116,9 @@ using namespace std;
   HOST_RESERVATION_IDENTIFIERS "host-reservation-identifiers"
 
   CLIENT_CLASSES "client-classes"
-  EVAL_CLIENT_CLASSES "eval-client-classes"
+  REQUIRED_CLIENT_CLASSES "required-client-classes"
   TEST "test"
-  EVAL_ON_DEMAND "eval-on-demand"
+  ONLY_IF_REQUIRED "only-if-required"
   CLIENT_CLASS "client-class"
 
   RESERVATIONS "reservations"
@@ -906,7 +906,7 @@ subnet6_param: preferred_lifetime
              | id
              | rapid_commit
              | client_class
-             | eval_client_classes
+             | required_client_classes
              | reservations
              | reservation_mode
              | relay
@@ -946,9 +946,9 @@ client_class: CLIENT_CLASS {
     ctx.leave();
 };
 
-eval_client_classes: EVAL_CLIENT_CLASSES {
+required_client_classes: REQUIRED_CLIENT_CLASSES {
     ElementPtr c(new ListElement(ctx.loc2pos(@1)));
-    ctx.stack_.back()->set("eval-client-classes", c);
+    ctx.stack_.back()->set("required-client-classes", c);
     ctx.stack_.push_back(c);
     ctx.enter(ctx.NO_KEYWORD);
 } COLON list_strings {
@@ -1023,7 +1023,7 @@ shared_network_param: name
                     | relay
                     | reservation_mode
                     | client_class
-                    | eval_client_classes
+                    | required_client_classes
                     | preferred_lifetime
                     | rapid_commit
                     | valid_lifetime
@@ -1307,7 +1307,7 @@ pool_params: pool_param
 pool_param: pool_entry
           | option_data_list
           | client_class
-          | eval_client_classes
+          | required_client_classes
           | user_context
           | unknown_map_entry
           ;
@@ -1383,7 +1383,7 @@ pd_pool_param: pd_prefix
              | pd_delegated_len
              | option_data_list
              | client_class
-             | eval_client_classes
+             | required_client_classes
              | excluded_prefix
              | excluded_prefix_len
              | user_context
@@ -1600,7 +1600,7 @@ not_empty_client_class_params: client_class_param
 
 client_class_param: client_class_name
                   | client_class_test
-                  | eval_on_demand
+                  | only_if_required
                   | option_data_list
                   | unknown_map_entry
                   ;
@@ -1615,9 +1615,9 @@ client_class_test: TEST {
     ctx.leave();
 };
 
-eval_on_demand: EVAL_ON_DEMAND COLON BOOLEAN {
+only_if_required: ONLY_IF_REQUIRED COLON BOOLEAN {
     ElementPtr b(new BoolElement($3, ctx.loc2pos(@3)));
-    ctx.stack_.back()->set("eval-on-demand", b);
+    ctx.stack_.back()->set("only-if-required", b);
 };
 
 // --- end of client classes ---------------------------------
diff --git a/src/bin/dhcp6/dhcp6_srv.cc b/src/bin/dhcp6/dhcp6_srv.cc
index cfdd446195..7c99b98b50 100644
--- a/src/bin/dhcp6/dhcp6_srv.cc
+++ b/src/bin/dhcp6/dhcp6_srv.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2011-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -2487,7 +2487,7 @@ Dhcpv6Srv::processSolicit(const Pkt6Ptr& solicit) {
     assignLeases(solicit, response, ctx);
 
     setReservedClientClasses(solicit, ctx);
-    lateClassify(solicit, ctx);
+    requiredClassify(solicit, ctx);
 
     copyClientOptions(solicit, response);
     CfgOptionList co_list;
@@ -2522,7 +2522,7 @@ Dhcpv6Srv::processRequest(const Pkt6Ptr& request) {
     assignLeases(request, reply, ctx);
 
     setReservedClientClasses(request, ctx);
-    lateClassify(request, ctx);
+    requiredClassify(request, ctx);
 
     copyClientOptions(request, reply);
     CfgOptionList co_list;
@@ -2553,7 +2553,7 @@ Dhcpv6Srv::processRenew(const Pkt6Ptr& renew) {
     extendLeases(renew, reply, ctx);
 
     setReservedClientClasses(renew, ctx);
-    lateClassify(renew, ctx);
+    requiredClassify(renew, ctx);
 
     copyClientOptions(renew, reply);
     CfgOptionList co_list;
@@ -2584,7 +2584,7 @@ Dhcpv6Srv::processRebind(const Pkt6Ptr& rebind) {
     extendLeases(rebind, reply, ctx);
 
     setReservedClientClasses(rebind, ctx);
-    lateClassify(rebind, ctx);
+    requiredClassify(rebind, ctx);
 
     copyClientOptions(rebind, reply);
     CfgOptionList co_list;
@@ -2609,7 +2609,7 @@ Dhcpv6Srv::processConfirm(const Pkt6Ptr& confirm) {
     AllocEngine::ClientContext6 ctx;
     initContext(confirm, ctx);
     setReservedClientClasses(confirm, ctx);
-    lateClassify(confirm, ctx);
+    requiredClassify(confirm, ctx);
 
     // Get IA_NAs from the Confirm. If there are none, the message is
     // invalid and must be discarded. There is nothing more to do.
@@ -2703,7 +2703,7 @@ Dhcpv6Srv::processRelease(const Pkt6Ptr& release) {
     AllocEngine::ClientContext6 ctx;
     initContext(release, ctx);
     setReservedClientClasses(release, ctx);
-    lateClassify(release, ctx);
+    requiredClassify(release, ctx);
 
     Pkt6Ptr reply(new Pkt6(DHCPV6_REPLY, release->getTransid()));
 
@@ -2733,7 +2733,7 @@ Dhcpv6Srv::processDecline(const Pkt6Ptr& decline) {
     AllocEngine::ClientContext6 ctx;
     initContext(decline, ctx);
     setReservedClientClasses(decline, ctx);
-    lateClassify(decline, ctx);
+    requiredClassify(decline, ctx);
 
     // Copy client options (client-id, also relay information if present)
     copyClientOptions(decline, reply);
@@ -3015,7 +3015,7 @@ Dhcpv6Srv::processInfRequest(const Pkt6Ptr& inf_request) {
     AllocEngine::ClientContext6 ctx;
     initContext(inf_request, ctx);
     setReservedClientClasses(inf_request, ctx);
-    lateClassify(inf_request, ctx);
+    requiredClassify(inf_request, ctx);
 
     // Create a Reply packet, with the same trans-id as the client's.
     Pkt6Ptr reply(new Pkt6(DHCPV6_REPLY, inf_request->getTransid()));
@@ -3102,8 +3102,8 @@ void Dhcpv6Srv::classifyPacket(const Pkt6Ptr& pkt) {
         if (!expr_ptr) {
             continue;
         }
-        // Not the right time if on demand
-        if ((*it)->getOnDemand()) {
+        // Not the right time if only when required
+        if ((*it)->getRequired()) {
             continue;
         }
         // Evaluate the expression which can return false (no match),
@@ -3154,8 +3154,8 @@ Dhcpv6Srv::setReservedClientClasses(const Pkt6Ptr& pkt,
 }
 
 void
-Dhcpv6Srv::lateClassify(const Pkt6Ptr& pkt, AllocEngine::ClientContext6& ctx) {
-    // First collect on-demand classes
+Dhcpv6Srv::requiredClassify(const Pkt6Ptr& pkt, AllocEngine::ClientContext6& ctx) {
+    // First collect required classes
     ClientClasses classes = pkt->getClasses(true);
     Subnet6Ptr subnet = ctx.subnet_;
 
@@ -3164,7 +3164,7 @@ Dhcpv6Srv::lateClassify(const Pkt6Ptr& pkt, AllocEngine::ClientContext6& ctx) {
         SharedNetwork6Ptr network;
         subnet->getSharedNetwork(network);
         if (network) {
-            const ClientClasses& to_add = network->getOnDemandClasses();
+            const ClientClasses& to_add = network->getRequiredClasses();
             for (ClientClasses::const_iterator cclass = to_add.cbegin();
                  cclass != to_add.cend(); ++cclass) {
                 classes.insert(*cclass);
@@ -3172,7 +3172,7 @@ Dhcpv6Srv::lateClassify(const Pkt6Ptr& pkt, AllocEngine::ClientContext6& ctx) {
         }
 
         // Followed by the subnet
-        const ClientClasses& to_add = subnet->getOnDemandClasses();
+        const ClientClasses& to_add = subnet->getRequiredClasses();
         for(ClientClasses::const_iterator cclass = to_add.cbegin();
             cclass != to_add.cend(); ++cclass) {
             classes.insert(*cclass);
@@ -3187,7 +3187,7 @@ Dhcpv6Srv::lateClassify(const Pkt6Ptr& pkt, AllocEngine::ClientContext6& ctx) {
                                                 resource.first,
                                                 false);
             if (pool) {
-                const ClientClasses& to_add = pool->getOnDemandClasses();
+                const ClientClasses& to_add = pool->getRequiredClasses();
                 for (ClientClasses::const_iterator cclass = to_add.cbegin();
                      cclass != to_add.cend(); ++cclass) {
                     classes.insert(*cclass);
@@ -3206,7 +3206,7 @@ Dhcpv6Srv::lateClassify(const Pkt6Ptr& pkt, AllocEngine::ClientContext6& ctx) {
          cclass != classes.cend(); ++cclass) {
         const ClientClassDefPtr class_def = dict->findClass(*cclass);
         if (!class_def) {
-            LOG_DEBUG(dhcp6_logger, DBG_DHCP6_BASIC, DHCP6_CLASS_UNKNOWN)
+            LOG_DEBUG(dhcp6_logger, DBG_DHCP6_BASIC, DHCP6_CLASS_UNDEFINED)
                 .arg(*cclass);
             continue;
         }
diff --git a/src/bin/dhcp6/dhcp6_srv.h b/src/bin/dhcp6/dhcp6_srv.h
index a63691f8ce..4f6a68a54e 100644
--- a/src/bin/dhcp6/dhcp6_srv.h
+++ b/src/bin/dhcp6/dhcp6_srv.h
@@ -1,4 +1,4 @@
-// Copyright (C) 2011-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2011-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -649,18 +649,18 @@ protected:
     void setReservedClientClasses(const Pkt6Ptr& pkt,
                                   const AllocEngine::ClientContext6& ctx);
 
-    /// @brief Assigns incoming packet to zero or more classes (late pass).
+    /// @brief Assigns incoming packet to zero or more classes (required pass).
     ///
-    /// @note This late classification evaluates all classes which
-    /// were marked for this deferred/on-demand pass. Classes are
-    /// collected in the reversed order than output option processing.
+    /// @note This required classification evaluates all classes which
+    /// were marked for required evaluation. Classes are collected so
+    /// evaluated in the reversed order than output option processing.
     ///
-    /// @note The eval-on-demand flag is related because it avoids
+    /// @note The only-if-required flag is related because it avoids
     /// double evaluation (which is not forbidden).
     ///
     /// @param pkt packet to be classified
     /// @param ctx allocation context where to get informations
-    void lateClassify(const Pkt6Ptr& pkt, AllocEngine::ClientContext6& ctx);
+    void requiredClassify(const Pkt6Ptr& pkt, AllocEngine::ClientContext6& ctx);
 
     /// @brief Attempts to get a MAC/hardware address using configured sources
     ///
diff --git a/src/bin/dhcp6/tests/classify_unittests.cc b/src/bin/dhcp6/tests/classify_unittests.cc
index 8fc19dcce0..99611da61e 100644
--- a/src/bin/dhcp6/tests/classify_unittests.cc
+++ b/src/bin/dhcp6/tests/classify_unittests.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2016-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2016-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -302,8 +302,8 @@ TEST_F(ClassifyTest, matchClassification) {
     EXPECT_FALSE(opt3);
 }
 
-// Check that on-demand classes are not evaluated by classifyPacket
-TEST_F(ClassifyTest, onDemand) {
+// Check that only-if-required classes are not evaluated by classifyPacket
+TEST_F(ClassifyTest, required) {
     IfaceMgrTestConfig test_config(true);
 
     NakedDhcpv6Srv srv(0);
@@ -329,7 +329,7 @@ TEST_F(ClassifyTest, onDemand) {
         "    \"interface\": \"eth1\" } ],"
         "\"client-classes\": [ "
         "{   \"name\": \"router\", "
-        "    \"eval-on-demand\": true, "
+        "    \"only-if-required\": true, "
         "    \"option-data\": ["
         "        {    \"name\": \"ipv6-forwarding\", "
         "             \"data\": \"true\" } ], "
@@ -391,8 +391,8 @@ TEST_F(ClassifyTest, onDemand) {
     EXPECT_FALSE(opt3);
 }
 
-// Checks that when requested on-demand classes are still (but late) evaluated
-TEST_F(ClassifyTest, lateClassification) {
+// Checks that when only-if-required classes are still evaluated
+TEST_F(ClassifyTest, requiredClassification) {
     IfaceMgrTestConfig test_config(true);
 
     NakedDhcpv6Srv srv(0);
@@ -415,11 +415,11 @@ TEST_F(ClassifyTest, lateClassification) {
         "\"subnet6\": [ "
         "{   \"pools\": [ { \"pool\": \"2001:db8:1::/64\" } ], "
         "    \"subnet\": \"2001:db8:1::/48\", "
-        "    \"eval-client-classes\": [ \"router\" ], "
+        "    \"require-client-classes\": [ \"router\" ], "
         "    \"interface\": \"eth1\" } ],"
         "\"client-classes\": [ "
         "{   \"name\": \"router\", "
-        "    \"eval-on-demand\": true, "
+        "    \"only-if-required\": true, "
         "    \"option-data\": ["
         "        {    \"name\": \"ipv6-forwarding\", "
         "             \"data\": \"true\" } ], "
@@ -1221,7 +1221,7 @@ TEST_F(ClassifyTest, member) {
     EXPECT_FALSE(ipf3->readBoolean());
 }
 
-// This test checks the precedence order in requested late evaluation.
+// This test checks the precedence order in required evaluation.
 // This order is: shared-network > subnet > pools
 TEST_F(ClassifyTest, precedenceNone) {
     std::string config =
@@ -1240,7 +1240,7 @@ TEST_F(ClassifyTest, precedenceNone) {
         "    {"
         "       \"name\": \"for-pool\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::1\""
@@ -1249,7 +1249,7 @@ TEST_F(ClassifyTest, precedenceNone) {
         "    {"
         "       \"name\": \"for-subnet\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::2\""
@@ -1258,7 +1258,7 @@ TEST_F(ClassifyTest, precedenceNone) {
         "    {"
         "       \"name\": \"for-network\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::3\""
@@ -1299,7 +1299,7 @@ TEST_F(ClassifyTest, precedenceNone) {
     EXPECT_FALSE(opt);
 }
 
-// This test checks the precedence order in requested late evaluation.
+// This test checks the precedence order in required evaluation.
 // This order is: shared-network > subnet > pools
 TEST_F(ClassifyTest, precedencePool) {
     std::string config =
@@ -1316,7 +1316,7 @@ TEST_F(ClassifyTest, precedencePool) {
         "    {"
         "       \"name\": \"for-pool\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::1\""
@@ -1325,7 +1325,7 @@ TEST_F(ClassifyTest, precedencePool) {
         "    {"
         "       \"name\": \"for-subnet\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::2\""
@@ -1334,7 +1334,7 @@ TEST_F(ClassifyTest, precedencePool) {
         "    {"
         "       \"name\": \"for-network\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::3\""
@@ -1349,7 +1349,7 @@ TEST_F(ClassifyTest, precedencePool) {
         "        \"id\": 1,"
         "        \"pools\": [ { "
         "            \"pool\": \"2001:db8:1::1 - 2001:db8:1::64\","
-        "            \"eval-client-classes\": [ \"for-pool\" ]"
+        "            \"require-client-classes\": [ \"for-pool\" ]"
         "        } ]"
         "    } ]"
         "} ],"
@@ -1382,7 +1382,7 @@ TEST_F(ClassifyTest, precedencePool) {
     EXPECT_EQ("2001:db8:1::1", addrs[0].toText());
 }
 
-// This test checks the precedence order in requested late evaluation.
+// This test checks the precedence order in required evaluation.
 // This order is: shared-network > subnet > pools
 TEST_F(ClassifyTest, precedenceSubnet) {
     std::string config =
@@ -1399,7 +1399,7 @@ TEST_F(ClassifyTest, precedenceSubnet) {
         "    {"
         "       \"name\": \"for-pool\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::1\""
@@ -1408,7 +1408,7 @@ TEST_F(ClassifyTest, precedenceSubnet) {
         "    {"
         "       \"name\": \"for-subnet\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::2\""
@@ -1417,7 +1417,7 @@ TEST_F(ClassifyTest, precedenceSubnet) {
         "    {"
         "       \"name\": \"for-network\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::3\""
@@ -1430,10 +1430,10 @@ TEST_F(ClassifyTest, precedenceSubnet) {
         "    \"subnet6\": [ { "
         "        \"subnet\": \"2001:db8:1::/64\","
         "        \"id\": 1,"
-        "        \"eval-client-classes\": [ \"for-subnet\" ],"
+        "        \"require-client-classes\": [ \"for-subnet\" ],"
         "        \"pools\": [ { "
         "            \"pool\": \"2001:db8:1::1 - 2001:db8:1::64\","
-        "            \"eval-client-classes\": [ \"for-pool\" ]"
+        "            \"require-client-classes\": [ \"for-pool\" ]"
         "        } ]"
         "    } ]"
         "} ],"
@@ -1466,7 +1466,7 @@ TEST_F(ClassifyTest, precedenceSubnet) {
     EXPECT_EQ("2001:db8:1::2", addrs[0].toText());
 }
 
-// This test checks the precedence order in requested late evaluation.
+// This test checks the precedence order in required evaluation.
 // This order is: shared-network > subnet > pools
 TEST_F(ClassifyTest, precedenceNetwork) {
     std::string config =
@@ -1483,7 +1483,7 @@ TEST_F(ClassifyTest, precedenceNetwork) {
         "    {"
         "       \"name\": \"for-pool\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::1\""
@@ -1492,7 +1492,7 @@ TEST_F(ClassifyTest, precedenceNetwork) {
         "    {"
         "       \"name\": \"for-subnet\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::2\""
@@ -1501,7 +1501,7 @@ TEST_F(ClassifyTest, precedenceNetwork) {
         "    {"
         "       \"name\": \"for-network\","
         "       \"test\": \"member('all')\","
-        "       \"eval-on-demand\": true,"
+        "       \"only-if-required\": true,"
         "       \"option-data\": [ {"
         "           \"name\": \"dns-servers\","
         "           \"data\": \"2001:db8:1::3\""
@@ -1511,14 +1511,14 @@ TEST_F(ClassifyTest, precedenceNetwork) {
         "\"shared-networks\": [ {"
         "    \"name\": \"frog\","
         "    \"interface\": \"eth1\","
-        "    \"eval-client-classes\": [ \"for-network\" ],"
+        "    \"require-client-classes\": [ \"for-network\" ],"
         "    \"subnet6\": [ { "
         "        \"subnet\": \"2001:db8:1::/64\","
         "        \"id\": 1,"
-        "        \"eval-client-classes\": [ \"for-subnet\" ],"
+        "        \"require-client-classes\": [ \"for-subnet\" ],"
         "        \"pools\": [ { "
         "            \"pool\": \"2001:db8:1::1 - 2001:db8:1::64\","
-        "            \"eval-client-classes\": [ \"for-pool\" ]"
+        "            \"require-client-classes\": [ \"for-pool\" ]"
         "        } ]"
         "    } ]"
         "} ],"
diff --git a/src/lib/dhcp/pkt.cc b/src/lib/dhcp/pkt.cc
index a6261802d5..cc7c2739cc 100644
--- a/src/lib/dhcp/pkt.cc
+++ b/src/lib/dhcp/pkt.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2014-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2014-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -97,8 +97,8 @@ Pkt::inClass(const std::string& client_class) {
 }
 
 void
-Pkt::addClass(const std::string& client_class, bool deferred) {
-    ClientClasses& classes = !deferred ? classes_ : on_demand_classes_;
+Pkt::addClass(const std::string& client_class, bool required) {
+    ClientClasses& classes = !required ? classes_ : required_classes_;
     if (!classes.contains(client_class)) {
         classes.insert(client_class);
     }
diff --git a/src/lib/dhcp/pkt.h b/src/lib/dhcp/pkt.h
index bde7a8500e..f2efc14de8 100644
--- a/src/lib/dhcp/pkt.h
+++ b/src/lib/dhcp/pkt.h
@@ -1,4 +1,4 @@
-// Copyright (C) 2014-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2014-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -285,18 +285,19 @@ public:
     /// so I decided to stick with addClass().
     ///
     /// @param client_class name of the class to be added
-    /// @param deferred the class is marked for late evaluation
+    /// @param required the class is marked for required evaluation
     void addClass(const isc::dhcp::ClientClass& client_class,
-                  bool deferred = false);
+                  bool required = false);
 
     /// @brief Returns the class set
     ///
     /// @note This should be used only to iterate over the class set.
-    /// @param deferred return classes or to be evaluated classes.
-    /// @return if deferred is false (the default) the claases the
-    /// packet belongs to else the classes which will be evaluated later.
-    const ClientClasses& getClasses(bool deferred = false) const {
-        return (!deferred ? classes_ : on_demand_classes_);
+    /// @param required return classes or required to be evaluated classes.
+    /// @return if required is false (the default) the classes the
+    /// packet belongs to else the classes which are required to be
+    /// evaluated.
+    const ClientClasses& getClasses(bool required = false) const {
+        return (!required ? classes_ : required_classes_);
     }
 
     /// @brief Unparsed data (in received packets).
@@ -585,13 +586,13 @@ public:
     /// @ref addClass should be used to operate on this field.
     ClientClasses classes_;
 
-    /// @brief Classes which will be evaluated later.
+    /// @brief Classes which are required to be evaluated.
     ///
     /// The comment on @ref classes_ applies here.
     ///
     /// Before output option processing these classes will be evaluated
     /// and if evaluation status is true added to the previous collection.
-    ClientClasses on_demand_classes_;
+    ClientClasses required_classes_;
 
     /// @brief Collection of options present in this message.
     ///
diff --git a/src/lib/dhcpsrv/client_class_def.cc b/src/lib/dhcpsrv/client_class_def.cc
index 0b85639bf2..91c9635164 100644
--- a/src/lib/dhcpsrv/client_class_def.cc
+++ b/src/lib/dhcpsrv/client_class_def.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2015-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2015-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -18,7 +18,7 @@ namespace dhcp {
 ClientClassDef::ClientClassDef(const std::string& name,
                                const ExpressionPtr& match_expr,
                                const CfgOptionPtr& cfg_option)
-    : name_(name), match_expr_(match_expr), on_demand_(false),
+    : name_(name), match_expr_(match_expr), required_(false),
       cfg_option_(cfg_option),
       next_server_(asiolink::IOAddress::IPV4_ZERO_ADDRESS()) {
 
@@ -38,7 +38,7 @@ ClientClassDef::ClientClassDef(const std::string& name,
 
 ClientClassDef::ClientClassDef(const ClientClassDef& rhs)
     : name_(rhs.name_), match_expr_(ExpressionPtr()),
-      on_demand_(false), cfg_option_(new CfgOption()),
+      required_(false), cfg_option_(new CfgOption()),
       next_server_(asiolink::IOAddress::IPV4_ZERO_ADDRESS()) {
 
     if (rhs.match_expr_) {
@@ -54,7 +54,7 @@ ClientClassDef::ClientClassDef(const ClientClassDef& rhs)
         rhs.cfg_option_->copyTo(*cfg_option_);
     }
 
-    on_demand_ = rhs.on_demand_;
+    required_ = rhs.required_;
     next_server_ = rhs.next_server_;
     sname_ = rhs.sname_;
     filename_ = rhs.filename_;
@@ -94,13 +94,13 @@ ClientClassDef::setTest(const std::string& test) {
 }
 
 bool
-ClientClassDef::getOnDemand() const {
-    return (on_demand_);
+ClientClassDef::getRequired() const {
+    return (required_);
 }
 
 void
-ClientClassDef::setOnDemand(bool on_demand) {
-    on_demand_ = on_demand;
+ClientClassDef::setRequired(bool required) {
+    required_ = required;
 }
 
 const CfgOptionDefPtr&
@@ -135,7 +135,7 @@ ClientClassDef::equals(const ClientClassDef& other) const {
         ((!cfg_option_def_ && !other.cfg_option_def_) ||
         (cfg_option_def_ && other.cfg_option_def_ &&
          (*cfg_option_def_ == *other.cfg_option_def_))) &&
-            (on_demand_ == other.on_demand_) &&
+            (required_ == other.required_) &&
             (next_server_ == other.next_server_) &&
             (sname_ == other.sname_) &&
             (filename_ == other.filename_));
@@ -151,9 +151,9 @@ ClientClassDef:: toElement() const {
     if (!test_.empty()) {
         result->set("test", Element::create(test_));
     }
-    // Set eval-on-demand
-    if (on_demand_) {
-        result->set("eval-on-demand", Element::create(on_demand_));
+    // Set only-if-required
+    if (required_) {
+        result->set("only-if-required", Element::create(required_));
     }
     // Set option-def (used only by DHCPv4)
     if (cfg_option_def_ && (family == AF_INET)) {
@@ -200,7 +200,7 @@ void
 ClientClassDictionary::addClass(const std::string& name,
                                 const ExpressionPtr& match_expr,
                                 const std::string& test,
-                                bool on_demand,
+                                bool required,
                                 const CfgOptionPtr& cfg_option,
                                 CfgOptionDefPtr cfg_option_def,
                                 asiolink::IOAddress next_server,
@@ -208,7 +208,7 @@ ClientClassDictionary::addClass(const std::string& name,
                                 const std::string& filename) {
     ClientClassDefPtr cclass(new ClientClassDef(name, match_expr, cfg_option));
     cclass->setTest(test);
-    cclass->setOnDemand(on_demand);
+    cclass->setRequired(required);
     cclass->setCfgOptionDef(cfg_option_def);
     cclass->setNextServer(next_server);
     cclass->setSname(sname);
diff --git a/src/lib/dhcpsrv/client_class_def.h b/src/lib/dhcpsrv/client_class_def.h
index b38263aba2..adcfe0e664 100644
--- a/src/lib/dhcpsrv/client_class_def.h
+++ b/src/lib/dhcpsrv/client_class_def.h
@@ -1,4 +1,4 @@
-// Copyright (C) 2015-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2015-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -82,11 +82,11 @@ public:
     /// @param test the original expression to assign the class
     void setTest(const std::string& test);
 
-    /// @brief Fetches the on demand flag
-    bool getOnDemand() const;
+    /// @brief Fetches the only if required flag
+    bool getRequired() const;
 
-    /// @brief Sets the on demand flag
-    void setOnDemand(bool on_demand);
+    /// @brief Sets the only if required flag
+    void setRequired(bool required);
 
     /// @brief Fetches the class's option definitions
     const CfgOptionDefPtr& getCfgOptionDef() const;
@@ -188,11 +188,11 @@ private:
     /// this class.
     std::string test_;
 
-    /// @brief The on demand flag: when false (the defaul) membership
+    /// @brief The only if required flag: when false (the defaul) membership
     /// is determined during classification so is for instance
     /// available for subnet selection, when true membership is evaluated
-    /// only if asked for and is usable only for option configuration.
-    bool on_demand_;
+    /// only when required for and is usable only for option configuration.
+    bool required_;
 
     /// @brief The option definition configuration for this class
     CfgOptionDefPtr cfg_option_def_;
@@ -251,7 +251,7 @@ public:
     /// @param name Name to assign to this class
     /// @param match_expr Expression the class will use to determine membership
     /// @param test Original version of match_expr
-    /// @param on_demand Original value of the on demand flag
+    /// @param required Original value of the only if required flag
     /// @param options Collection of options members should be given
     /// @param defs Option definitions (optional)
     /// @param next_server next-server value for this class (optional)
@@ -262,7 +262,7 @@ public:
     /// dictionary.  See @ref dhcp::ClientClassDef::ClientClassDef() for
     /// others.
     void addClass(const std::string& name, const ExpressionPtr& match_expr,
-                  const std::string& test, bool on_demand,
+                  const std::string& test, bool required,
                   const CfgOptionPtr& options,
                   CfgOptionDefPtr defs = CfgOptionDefPtr(),
                   asiolink::IOAddress next_server = asiolink::IOAddress("0.0.0.0"),
diff --git a/src/lib/dhcpsrv/network.cc b/src/lib/dhcpsrv/network.cc
index 9ba52a8598..0c48dba822 100644
--- a/src/lib/dhcpsrv/network.cc
+++ b/src/lib/dhcpsrv/network.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2017-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -37,15 +37,15 @@ Network::allowClientClass(const isc::dhcp::ClientClass& class_name) {
 }
 
 void
-Network::deferClientClass(const isc::dhcp::ClientClass& class_name) {
-    if (!on_demand_classes_.contains(class_name)) {
-        on_demand_classes_.insert(class_name);
+Network::requireClientClass(const isc::dhcp::ClientClass& class_name) {
+    if (!required_classes_.contains(class_name)) {
+        required_classes_.insert(class_name);
     }
 }
 
 const ClientClasses&
-Network::getOnDemandClasses() const {
-    return (on_demand_classes_);
+Network::getRequiredClasses() const {
+    return (required_classes_);
 }
 
 ElementPtr
@@ -70,15 +70,15 @@ Network::toElement() const {
         map->set("client-class", Element::create(cclass));
     }
 
-    // Set eval-client-classes
-    const ClientClasses& classes = getOnDemandClasses();
+    // Set required-client-classes
+    const ClientClasses& classes = getRequiredClasses();
     if (!classes.empty()) {
         ElementPtr class_list = Element::createList();
         for (ClientClasses::const_iterator it = classes.cbegin();
              it != classes.cend(); ++it) {
             class_list->add(Element::create(*it));
         }
-        map->set("eval-client-classes", class_list);
+        map->set("required-client-classes", class_list);
     }
 
     // Set renew-timer
diff --git a/src/lib/dhcpsrv/network.h b/src/lib/dhcpsrv/network.h
index b34eb6e424..40ffe93010 100644
--- a/src/lib/dhcpsrv/network.h
+++ b/src/lib/dhcpsrv/network.h
@@ -1,4 +1,4 @@
-// Copyright (C) 2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2017-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -172,13 +172,13 @@ public:
     /// @param class_name client class to be supported by this network
     void allowClientClass(const isc::dhcp::ClientClass& class_name);
 
-    /// @brief Adds class class_name to classes to be evaluated later
+    /// @brief Adds class class_name to classes required to be evaluated.
     ///
-    /// @param class_name client class to be evaluated later
-    void deferClientClass(const isc::dhcp::ClientClass& class_name);
+    /// @param class_name client class required to be evaluated
+    void requireClientClass(const isc::dhcp::ClientClass& class_name);
 
-    /// @brief Returns classes which will be evaluated later
-    const isc::dhcp::ClientClasses& getOnDemandClasses() const;
+    /// @brief Returns classes which are required to be evaluated
+    const isc::dhcp::ClientClasses& getRequiredClasses() const;
 
     /// @brief returns the client class
     ///
@@ -281,11 +281,11 @@ protected:
     /// which means that any client is allowed, regardless of its class.
     ClientClass client_class_;
 
-    /// @brief On demand classes
+    /// @brief Required classes
     ///
     /// If the network is selected these classes will be added to the
-    /// incoming packet and evaluated later.
-    ClientClasses on_demand_classes_;
+    /// incoming packet and their evaluation will be required.
+    ClientClasses required_classes_;
 
     /// @brief a Triplet (min/default/max) holding allowed renew timer values
     Triplet<uint32_t> t1_;
diff --git a/src/lib/dhcpsrv/parsers/client_class_def_parser.cc b/src/lib/dhcpsrv/parsers/client_class_def_parser.cc
index cf4b231bbe..1e4714203a 100644
--- a/src/lib/dhcpsrv/parsers/client_class_def_parser.cc
+++ b/src/lib/dhcpsrv/parsers/client_class_def_parser.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2015-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2015-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -132,10 +132,10 @@ ClientClassDefParser::parse(ClientClassDictionaryPtr& class_dictionary,
         opts_parser.parse(options, option_data);
     }
 
-    // Let's try to parse the eval-on-demand flag
-    bool on_demand = false;
-    if (class_def_cfg->contains("eval-on-demand")) {
-        on_demand = getBoolean(class_def_cfg, "eval-on-demand");
+    // Let's try to parse the only-if-required flag
+    bool required = false;
+    if (class_def_cfg->contains("only-if-required")) {
+        required = getBoolean(class_def_cfg, "only-if-required");
     }
 
     // Let's try to parse the next-server field
@@ -193,7 +193,7 @@ ClientClassDefParser::parse(ClientClassDictionaryPtr& class_dictionary,
 
     // Add the client class definition
     try {
-        class_dictionary->addClass(name, match_expr, test, on_demand, options,
+        class_dictionary->addClass(name, match_expr, test, required, options,
                                    defs, next_server, sname, filename);
     } catch (const std::exception& ex) {
         isc_throw(DhcpConfigError, "Can't add class: " << ex.what()
diff --git a/src/lib/dhcpsrv/parsers/dhcp_parsers.cc b/src/lib/dhcpsrv/parsers/dhcp_parsers.cc
index 4c41cbf848..ce1879f97c 100644
--- a/src/lib/dhcpsrv/parsers/dhcp_parsers.cc
+++ b/src/lib/dhcpsrv/parsers/dhcp_parsers.cc
@@ -388,8 +388,8 @@ PoolParser::parse(PoolStoragePtr pools,
         }
     }
 
-    // Try setting up on demand client classes.
-    ConstElementPtr class_list = pool_structure->get("eval-client-classes");
+    // Try setting up required client classes.
+    ConstElementPtr class_list = pool_structure->get("required-client-classes");
     if (class_list) {
         const std::vector<data::ElementPtr>& classes = class_list->listValue();
         for (auto cclass = classes.cbegin();
@@ -399,7 +399,7 @@ PoolParser::parse(PoolStoragePtr pools,
                 isc_throw(DhcpConfigError, "invalid class name ("
                           << (*cclass)->getPosition() << ")");
             }
-            pool->deferClientClass((*cclass)->stringValue());
+            pool->requireClientClass((*cclass)->stringValue());
         }
     }
 }
@@ -711,8 +711,8 @@ Subnet4ConfigParser::initSubnet(data::ConstElementPtr params,
         subnet4->allowClientClass(client_class);
     }
 
-    // Try setting up on demand client classes.
-    ConstElementPtr class_list = params->get("eval-client-classes");
+    // Try setting up required client classes.
+    ConstElementPtr class_list = params->get("required-client-classes");
     if (class_list) {
         const std::vector<data::ElementPtr>& classes = class_list->listValue();
         for (auto cclass = classes.cbegin();
@@ -722,7 +722,7 @@ Subnet4ConfigParser::initSubnet(data::ConstElementPtr params,
                 isc_throw(DhcpConfigError, "invalid class name ("
                           << (*cclass)->getPosition() << ")");
             }
-            subnet4->deferClientClass((*cclass)->stringValue());
+            subnet4->requireClientClass((*cclass)->stringValue());
         }
     }
 
@@ -891,7 +891,7 @@ PdPoolParser::parse(PoolStoragePtr pools, ConstElementPtr pd_pool_) {
         client_class_ = client_class;
     }
 
-    ConstElementPtr class_list = pd_pool_->get("eval-client-classes");
+    ConstElementPtr class_list = pd_pool_->get("required-client-classes");
 
     // Check the pool parameters. It will throw an exception if any
     // of the required parameters are invalid.
@@ -932,7 +932,7 @@ PdPoolParser::parse(PoolStoragePtr pools, ConstElementPtr pd_pool_) {
                 isc_throw(DhcpConfigError, "invalid class name ("
                           << (*cclass)->getPosition() << ")");
             }
-            pool_->deferClientClass((*cclass)->stringValue());
+            pool_->requireClientClass((*cclass)->stringValue());
         }
     }
 
@@ -1111,8 +1111,8 @@ Subnet6ConfigParser::initSubnet(data::ConstElementPtr params,
         subnet6->allowClientClass(client_class);
     }
 
-    // Try setting up on demand client classes.
-    ConstElementPtr class_list = params->get("eval-client-classes");
+    // Try setting up required client classes.
+    ConstElementPtr class_list = params->get("required-client-classes");
     if (class_list) {
         const std::vector<data::ElementPtr>& classes = class_list->listValue();
         for (auto cclass = classes.cbegin();
@@ -1122,7 +1122,7 @@ Subnet6ConfigParser::initSubnet(data::ConstElementPtr params,
                 isc_throw(DhcpConfigError, "invalid class name ("
                           << (*cclass)->getPosition() << ")");
             }
-            subnet6->deferClientClass((*cclass)->stringValue());
+            subnet6->requireClientClass((*cclass)->stringValue());
         }
     }
 
diff --git a/src/lib/dhcpsrv/parsers/shared_network_parser.cc b/src/lib/dhcpsrv/parsers/shared_network_parser.cc
index 91c104fdef..5a04e6cd20 100644
--- a/src/lib/dhcpsrv/parsers/shared_network_parser.cc
+++ b/src/lib/dhcpsrv/parsers/shared_network_parser.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2017-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -70,9 +70,9 @@ SharedNetwork4Parser::parse(const data::ConstElementPtr& shared_network_data) {
             }
         }
 
-        if (shared_network_data->contains("eval-client-classes")) {
+        if (shared_network_data->contains("required-client-classes")) {
             const std::vector<data::ElementPtr>& class_list =
-                shared_network_data->get("eval-client-classes")->listValue();
+                shared_network_data->get("required-client-classes")->listValue();
             for (auto cclass = class_list.cbegin();
                  cclass != class_list.cend(); ++cclass) {
                 if (((*cclass)->getType() != Element::string) ||
@@ -80,7 +80,7 @@ SharedNetwork4Parser::parse(const data::ConstElementPtr& shared_network_data) {
                     isc_throw(DhcpConfigError, "invalid class name ("
                               << (*cclass)->getPosition() << ")");
                 }
-                shared_network->deferClientClass((*cclass)->stringValue());
+                shared_network->requireClientClass((*cclass)->stringValue());
             }
         }
 
@@ -125,9 +125,9 @@ SharedNetwork6Parser::parse(const data::ConstElementPtr& shared_network_data) {
             }
         }
 
-        if (shared_network_data->contains("eval-client-classes")) {
+        if (shared_network_data->contains("required-client-classes")) {
             const std::vector<data::ElementPtr>& class_list =
-                shared_network_data->get("eval-client-classes")->listValue();
+                shared_network_data->get("required-client-classes")->listValue();
             for (auto cclass = class_list.cbegin();
                  cclass != class_list.cend(); ++cclass) {
                 if (((*cclass)->getType() != Element::string) ||
@@ -135,7 +135,7 @@ SharedNetwork6Parser::parse(const data::ConstElementPtr& shared_network_data) {
                     isc_throw(DhcpConfigError, "invalid class name ("
                               << (*cclass)->getPosition() << ")");
                 }
-                shared_network->deferClientClass((*cclass)->stringValue());
+                shared_network->requireClientClass((*cclass)->stringValue());
             }
         }
 
diff --git a/src/lib/dhcpsrv/pool.cc b/src/lib/dhcpsrv/pool.cc
index edc5db276a..2e96ee1ded 100644
--- a/src/lib/dhcpsrv/pool.cc
+++ b/src/lib/dhcpsrv/pool.cc
@@ -112,15 +112,15 @@ Pool::toElement() const {
         map->set("client-class", Element::create(cclass));
     }
 
-    // Set eval-client-classes
-    const ClientClasses& classes = getOnDemandClasses();
+    // Set required-client-classes
+    const ClientClasses& classes = getRequiredClasses();
     if (!classes.empty()) {
         ElementPtr class_list =Element::createList();
         for (ClientClasses::const_iterator it = classes.cbegin();
              it != classes.cend(); ++it) {
             class_list->add(Element::create(*it));
         }
-        map->set("eval-client-classes", class_list);
+        map->set("required-client-classes", class_list);
     }
 
     return (map);
diff --git a/src/lib/dhcpsrv/pool.h b/src/lib/dhcpsrv/pool.h
index a1ae604a8d..30d1e2f7ed 100644
--- a/src/lib/dhcpsrv/pool.h
+++ b/src/lib/dhcpsrv/pool.h
@@ -129,18 +129,18 @@ public:
         return (client_class_);
     }
 
-    /// @brief Adds class class_name to classes to be evaluated later
+    /// @brief Adds class class_name to classes required to be evaluated
     ///
-    /// @param class_name client class to be evaluated later
-    void deferClientClass(const ClientClass& class_name) {
-        if (!on_demand_classes_.contains(class_name)) {
-            on_demand_classes_.insert(class_name);
+    /// @param class_name client class required to be evaluated
+    void requireClientClass(const ClientClass& class_name) {
+        if (!required_classes_.contains(class_name)) {
+            required_classes_.insert(class_name);
         }
     }
 
-    /// @brief Returns classes which will be evaluated later
-    const ClientClasses& getOnDemandClasses() const {
-        return (on_demand_classes_);
+    /// @brief Returns classes which are required to be evaluated
+    const ClientClasses& getRequiredClasses() const {
+        return (required_classes_);
     }
 
     /// @brief returns the last address that was tried from this pool
@@ -232,10 +232,10 @@ protected:
     /// @ref Network::client_class_
     ClientClass client_class_;
 
-    /// @brief On demand classes
+    /// @brief Required classes
     ///
-    /// @ref isc::dhcp::Network::on_demand_classes
-    ClientClasses on_demand_classes_;
+    /// @ref isc::dhcp::Network::required_classes
+    ClientClasses required_classes_;
 
     /// @brief Pointer to the user context (may be NULL)
     data::ConstElementPtr user_context_;
diff --git a/src/lib/dhcpsrv/tests/cfg_subnets4_unittest.cc b/src/lib/dhcpsrv/tests/cfg_subnets4_unittest.cc
index c142dfa520..8f8c691d87 100644
--- a/src/lib/dhcpsrv/tests/cfg_subnets4_unittest.cc
+++ b/src/lib/dhcpsrv/tests/cfg_subnets4_unittest.cc
@@ -739,8 +739,8 @@ TEST(CfgSubnets4Test, unparseSubnet) {
     subnet2->setIface("lo");
     subnet2->setRelayInfo(IOAddress("10.0.0.1"));
     subnet3->setIface("eth1");
-    subnet3->deferClientClass("foo");
-    subnet3->deferClientClass("bar");
+    subnet3->requireClientClass("foo");
+    subnet3->requireClientClass("bar");
 
     cfg.add(subnet1);
     cfg.add(subnet2);
@@ -802,7 +802,7 @@ TEST(CfgSubnets4Test, unparseSubnet) {
         "    \"reservation-mode\": \"all\",\n"
         "    \"option-data\": [ ],\n"
         "    \"pools\": [ ]\n,"
-        "    \"eval-client-classes\": [ \"foo\", \"bar\" ]\n"
+        "    \"required-client-classes\": [ \"foo\", \"bar\" ]\n"
         "} ]\n";
     runToElementTest<CfgSubnets4>(expected, cfg);
 }
@@ -816,7 +816,7 @@ TEST(CfgSubnets4Test, unparsePool) {
     Pool4Ptr pool1(new Pool4(IOAddress("192.0.2.1"), IOAddress("192.0.2.10")));
     Pool4Ptr pool2(new Pool4(IOAddress("192.0.2.64"), 26));
     pool2->allowClientClass("bar");
-    pool2->deferClientClass("foo");
+    pool2->requireClientClass("foo");
 
     subnet->addPool(pool1);
     subnet->addPool(pool2);
@@ -848,7 +848,7 @@ TEST(CfgSubnets4Test, unparsePool) {
         "            \"option-data\": [ ],\n"
         "            \"pool\": \"192.0.2.64/26\",\n"
         "            \"client-class\": \"bar\",\n"
-        "            \"eval-client-classes\": [ \"foo\" ]\n"
+        "            \"required-client-classes\": [ \"foo\" ]\n"
         "        }\n"
         "    ]\n"
         "} ]\n";
diff --git a/src/lib/dhcpsrv/tests/cfg_subnets6_unittest.cc b/src/lib/dhcpsrv/tests/cfg_subnets6_unittest.cc
index 63c3297247..6d1f6baad4 100644
--- a/src/lib/dhcpsrv/tests/cfg_subnets6_unittest.cc
+++ b/src/lib/dhcpsrv/tests/cfg_subnets6_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2014-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2014-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -438,8 +438,8 @@ TEST(CfgSubnets6Test, unparseSubnet) {
     subnet2->setIface("lo");
     subnet2->setRelayInfo(IOAddress("2001:db8:ff::2"));
     subnet3->setIface("eth1");
-    subnet3->deferClientClass("foo");
-    subnet3->deferClientClass("bar");
+    subnet3->requireClientClass("foo");
+    subnet3->requireClientClass("bar");
 
     cfg.add(subnet1);
     cfg.add(subnet2);
@@ -490,7 +490,7 @@ TEST(CfgSubnets6Test, unparseSubnet) {
         "    \"pools\": [ ],\n"
         "    \"pd-pools\": [ ],\n"
         "    \"option-data\": [ ],\n"
-        "    \"eval-client-classes\": [ \"foo\", \"bar\" ]\n"
+        "    \"required-client-classes\": [ \"foo\", \"bar\" ]\n"
         "} ]\n";
     runToElementTest<CfgSubnets6>(expected, cfg);
 }
@@ -507,7 +507,7 @@ TEST(CfgSubnets6Test, unparsePool) {
                              IOAddress("2001:db8:1::199")));
     Pool6Ptr pool2(new Pool6(Lease::TYPE_NA, IOAddress("2001:db8:1:1::"), 64));
     pool2->allowClientClass("bar");
-    pool2->deferClientClass("foo");
+    pool2->requireClientClass("foo");
 
     subnet->addPool(pool1);
     subnet->addPool(pool2);
@@ -533,7 +533,7 @@ TEST(CfgSubnets6Test, unparsePool) {
         "            \"pool\": \"2001:db8:1:1::/64\",\n"
         "            \"option-data\": [ ],\n"
         "            \"client-class\": \"bar\",\n"
-        "            \"eval-client-classes\": [ \"foo\" ]\n"
+        "            \"required-client-classes\": [ \"foo\" ]\n"
         "        }\n"
         "    ],\n"
         "    \"pd-pools\": [ ],\n"
@@ -554,7 +554,7 @@ TEST(CfgSubnets6Test, unparsePdPool) {
                                IOAddress("2001:db8:2::"), 48, 64));
     Pool6Ptr pdpool2(new Pool6(IOAddress("2001:db8:3::"), 48, 56,
                                IOAddress("2001:db8:3::"), 64));
-    pdpool1->deferClientClass("bar");
+    pdpool1->requireClientClass("bar");
     pdpool2->allowClientClass("bar");
 
     subnet->addPool(pdpool1);
@@ -580,7 +580,7 @@ TEST(CfgSubnets6Test, unparsePdPool) {
         "            \"prefix-len\": 48,\n"
         "            \"delegated-len\": 64,\n"
         "            \"option-data\": [ ],\n"
-        "            \"eval-client-classes\": [ \"bar\" ]\n"
+        "            \"required-client-classes\": [ \"bar\" ]\n"
         "        },{\n"
         "            \"prefix\": \"2001:db8:3::\",\n"
         "            \"prefix-len\": 48,\n"
diff --git a/src/lib/dhcpsrv/tests/client_class_def_unittest.cc b/src/lib/dhcpsrv/tests/client_class_def_unittest.cc
index 816d100c96..9d8eabb27d 100644
--- a/src/lib/dhcpsrv/tests/client_class_def_unittest.cc
+++ b/src/lib/dhcpsrv/tests/client_class_def_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2015-2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2015-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -142,10 +142,10 @@ TEST(ClientClassDef, copyAndEquality) {
     EXPECT_TRUE(*cclass == *cclass2);
     EXPECT_FALSE(*cclass != *cclass2);
 
-    // Verify the on_demand flag is enough to make classes not equal.
-    EXPECT_FALSE(cclass->getOnDemand());
-    cclass2->setOnDemand(true);
-    EXPECT_TRUE(cclass2->getOnDemand());
+    // Verify the required flag is enough to make classes not equal.
+    EXPECT_FALSE(cclass->getRequired());
+    cclass2->setRequired(true);
+    EXPECT_TRUE(cclass2->getRequired());
     EXPECT_FALSE(*cclass == *cclass2);
     EXPECT_TRUE(*cclass != *cclass2);
 
@@ -346,7 +346,7 @@ TEST(ClientClassDef, fixedFieldsDefaults) {
     ASSERT_NO_THROW(cclass.reset(new ClientClassDef(name, expr)));
 
     // Let's checks that it doesn't return any nonsense
-    EXPECT_FALSE(cclass->getOnDemand());
+    EXPECT_FALSE(cclass->getRequired());
     EXPECT_FALSE(cclass->getCfgOptionDef());
     string empty;
     ASSERT_EQ(IOAddress("0.0.0.0"), cclass->getNextServer());
@@ -369,7 +369,7 @@ TEST(ClientClassDef, fixedFieldsBasics) {
     // Verify we can create a class with a name, expression, and no cfg_option
     ASSERT_NO_THROW(cclass.reset(new ClientClassDef(name, expr)));
 
-    cclass->setOnDemand(true);
+    cclass->setRequired(true);
 
     string sname = "This is a very long string that can be a server name";
     string filename = "this-is-a-slightly-longish-name-of-a-file.txt";
@@ -379,7 +379,7 @@ TEST(ClientClassDef, fixedFieldsBasics) {
     cclass->setFilename(filename);
 
     // Let's checks that it doesn't return any nonsense
-    EXPECT_TRUE(cclass->getOnDemand());
+    EXPECT_TRUE(cclass->getRequired());
     EXPECT_EQ(IOAddress("1.2.3.4"), cclass->getNextServer());
     EXPECT_EQ(sname, cclass->getSname());
     EXPECT_EQ(filename, cclass->getFilename());
@@ -397,7 +397,7 @@ TEST(ClientClassDef, unparseDef) {
     ASSERT_NO_THROW(cclass.reset(new ClientClassDef(name, expr)));
     std::string test = "option[12].text == 'foo'";
     cclass->setTest(test);
-    cclass->setOnDemand(true);
+    cclass->setRequired(true);
     std::string next_server = "1.2.3.4";
     cclass->setNextServer(IOAddress(next_server));
     std::string sname = "my-server.example.com";
@@ -409,7 +409,7 @@ TEST(ClientClassDef, unparseDef) {
     std::string expected = "{\n"
         "\"name\": \"" + name + "\",\n"
         "\"test\": \"" + test + "\",\n"
-        "\"eval-on-demand\": true,\n"
+        "\"only-if-required\": true,\n"
         "\"next-server\": \"" + next_server + "\",\n"
         "\"server-hostname\": \"" + sname + "\",\n"
         "\"boot-file-name\": \"" + filename + "\",\n"
diff --git a/src/lib/dhcpsrv/tests/pool_unittest.cc b/src/lib/dhcpsrv/tests/pool_unittest.cc
index 6f6b8192f5..a0e113668b 100644
--- a/src/lib/dhcpsrv/tests/pool_unittest.cc
+++ b/src/lib/dhcpsrv/tests/pool_unittest.cc
@@ -230,33 +230,33 @@ TEST(Pool4Test, clientClass) {
     EXPECT_TRUE(pool->clientSupported(three_classes));
 }
 
-// This test checks that handling for eval-client-classes is valid.
-TEST(Pool4Test, onDemandClasses) {
+// This test checks that handling for required-client-classes is valid.
+TEST(Pool4Test, requiredClasses) {
     // Create a pool.
     Pool4Ptr pool(new Pool4(IOAddress("192.0.2.0"),
                             IOAddress("192.0.2.255")));
 
-    // This client starts with no deferred classes.
-    EXPECT_TRUE(pool->getOnDemandClasses().empty());
+    // This client starts with no required classes.
+    EXPECT_TRUE(pool->getRequiredClasses().empty());
 
     // Add the first class
-    pool->deferClientClass("router");
-    EXPECT_EQ(1, pool->getOnDemandClasses().size());
+    pool->requireClientClass("router");
+    EXPECT_EQ(1, pool->getRequiredClasses().size());
 
     // Add a second class
-    pool->deferClientClass("modem");
-    EXPECT_EQ(2, pool->getOnDemandClasses().size());
-    EXPECT_TRUE(pool->getOnDemandClasses().contains("router"));
-    EXPECT_TRUE(pool->getOnDemandClasses().contains("modem"));
-    EXPECT_FALSE(pool->getOnDemandClasses().contains("foo"));
+    pool->requireClientClass("modem");
+    EXPECT_EQ(2, pool->getRequiredClasses().size());
+    EXPECT_TRUE(pool->getRequiredClasses().contains("router"));
+    EXPECT_TRUE(pool->getRequiredClasses().contains("modem"));
+    EXPECT_FALSE(pool->getRequiredClasses().contains("foo"));
 
     // Check that it's ok to add the same class repeatedly
-    EXPECT_NO_THROW(pool->deferClientClass("foo"));
-    EXPECT_NO_THROW(pool->deferClientClass("foo"));
-    EXPECT_NO_THROW(pool->deferClientClass("foo"));
+    EXPECT_NO_THROW(pool->requireClientClass("foo"));
+    EXPECT_NO_THROW(pool->requireClientClass("foo"));
+    EXPECT_NO_THROW(pool->requireClientClass("foo"));
 
-    // Check that 'foo' is marked for late evaluation
-    EXPECT_TRUE(pool->getOnDemandClasses().contains("foo"));
+    // Check that 'foo' is marked for required evaluation
+    EXPECT_TRUE(pool->getRequiredClasses().contains("foo"));
 }
 
 // This test checks that handling for last allocated address/prefix is valid.
@@ -625,33 +625,33 @@ TEST(Pool6Test, clientClass) {
     EXPECT_TRUE(pool.clientSupported(three_classes));
 }
 
-// This test checks that handling for eval-client-classes is valid.
-TEST(Pool6Test, onDemandClasses) {
+// This test checks that handling for required-client-classes is valid.
+TEST(Pool6Test, requiredClasses) {
     // Create a pool.
     Pool6 pool(Lease::TYPE_NA, IOAddress("2001:db8::1"),
                IOAddress("2001:db8::2"));
 
-    // This client starts with no deferred classes.
-    EXPECT_TRUE(pool.getOnDemandClasses().empty());
+    // This client starts with no required classes.
+    EXPECT_TRUE(pool.getRequiredClasses().empty());
 
     // Add the first class
-    pool.deferClientClass("router");
-    EXPECT_EQ(1, pool.getOnDemandClasses().size());
+    pool.requireClientClass("router");
+    EXPECT_EQ(1, pool.getRequiredClasses().size());
 
     // Add a second class
-    pool.deferClientClass("modem");
-    EXPECT_EQ(2, pool.getOnDemandClasses().size());
-    EXPECT_TRUE(pool.getOnDemandClasses().contains("router"));
-    EXPECT_TRUE(pool.getOnDemandClasses().contains("modem"));
-    EXPECT_FALSE(pool.getOnDemandClasses().contains("foo"));
+    pool.requireClientClass("modem");
+    EXPECT_EQ(2, pool.getRequiredClasses().size());
+    EXPECT_TRUE(pool.getRequiredClasses().contains("router"));
+    EXPECT_TRUE(pool.getRequiredClasses().contains("modem"));
+    EXPECT_FALSE(pool.getRequiredClasses().contains("foo"));
 
     // Check that it's ok to add the same class repeatedly
-    EXPECT_NO_THROW(pool.deferClientClass("foo"));
-    EXPECT_NO_THROW(pool.deferClientClass("foo"));
-    EXPECT_NO_THROW(pool.deferClientClass("foo"));
+    EXPECT_NO_THROW(pool.requireClientClass("foo"));
+    EXPECT_NO_THROW(pool.requireClientClass("foo"));
+    EXPECT_NO_THROW(pool.requireClientClass("foo"));
 
-    // Check that 'foo' is marked for late evaluation
-    EXPECT_TRUE(pool.getOnDemandClasses().contains("foo"));
+    // Check that 'foo' is marked for required evaluation
+    EXPECT_TRUE(pool.getRequiredClasses().contains("foo"));
 }
 
 // This test checks that handling for last allocated address/prefix is valid.
diff --git a/src/lib/dhcpsrv/tests/shared_network_parser_unittest.cc b/src/lib/dhcpsrv/tests/shared_network_parser_unittest.cc
index dee9300e6a..dfb3a9db9c 100644
--- a/src/lib/dhcpsrv/tests/shared_network_parser_unittest.cc
+++ b/src/lib/dhcpsrv/tests/shared_network_parser_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2017-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -52,7 +52,7 @@ public:
                 "            \"server-hostname\": \"\","
                 "            \"boot-file-name\": \"\","
                 "            \"client-class\": \"\","
-                "            \"eval-client-classes\": []\n,"
+                "            \"required-client-classes\": []\n,"
                 "            \"reservation-mode\": \"all\","
                 "            \"4o6-interface\": \"\","
                 "            \"4o6-interface-id\": \"\","
@@ -73,7 +73,7 @@ public:
                 "            \"server-hostname\": \"\","
                 "            \"boot-file-name\": \"\","
                 "            \"client-class\": \"\","
-                "            \"eval-client-classes\": []\n,"
+                "            \"required-client-classes\": []\n,"
                 "            \"reservation-mode\": \"all\","
                 "            \"4o6-interface\": \"\","
                 "            \"4o6-interface-id\": \"\","
@@ -194,7 +194,7 @@ public:
                 "            \"preferred-lifetime\": 300,"
                 "            \"valid-lifetime\": 400,"
                 "            \"client-class\": \"\","
-                "            \"eval-client-classes\": []\n,"
+                "            \"required-client-classes\": []\n,"
                 "            \"reservation-mode\": \"all\","
                 "            \"decline-probation-period\": 86400,"
                 "            \"dhcp4o6-port\": 0,"
@@ -210,7 +210,7 @@ public:
                 "            \"preferred-lifetime\": 30,"
                 "            \"valid-lifetime\": 40,"
                 "            \"client-class\": \"\","
-                "            \"eval-client-classes\": []\n,"
+                "            \"required-client-classes\": []\n,"
                 "            \"reservation-mode\": \"all\","
                 "            \"decline-probation-period\": 86400,"
                 "            \"dhcp4o6-port\": 0,"
@@ -283,7 +283,7 @@ TEST_F(SharedNetwork6ParserTest, clientClass) {
     EXPECT_EQ("alpha", network->getClientClass());
 }
 
-// This test verifies that it's possible to specify eval-client-classes
+// This test verifies that it's possible to specify required-client-classes
 // on shared-network level.
 TEST_F(SharedNetwork6ParserTest, evalClientClasses) {
     std::string config = getWorkingConfig();
@@ -292,7 +292,7 @@ TEST_F(SharedNetwork6ParserTest, evalClientClasses) {
     ElementPtr class_list = Element::createList();
     class_list->add(Element::create("alpha"));
     class_list->add(Element::create("beta"));
-    config_element->set("eval-client-classes", class_list);
+    config_element->set("required-client-classes", class_list);
 
     // Parse configuration specified above.
     SharedNetwork6Parser parser;
@@ -300,12 +300,12 @@ TEST_F(SharedNetwork6ParserTest, evalClientClasses) {
     network = parser.parse(config_element);
     ASSERT_TRUE(network);
 
-    const ClientClasses& classes = network->getOnDemandClasses();
+    const ClientClasses& classes = network->getRequiredClasses();
     EXPECT_EQ(2, classes.size());
     EXPECT_EQ("alpha, beta", classes.toText());
 }
 
-// This test verifies that bad eval-client-classes configs raise
+// This test verifies that bad required-client-classes configs raise
 // expected errors.
 TEST_F(SharedNetwork6ParserTest, badEvalClientClasses) {
     std::string config = getWorkingConfig();
@@ -315,7 +315,7 @@ TEST_F(SharedNetwork6ParserTest, badEvalClientClasses) {
     ElementPtr class_list = Element::createList();
     class_list->add(Element::create("alpha"));
     class_list->add(Element::create(1234));
-    config_element->set("eval-client-classes", class_list);
+    config_element->set("required-client-classes", class_list);
 
     // Parse configuration specified above.
     SharedNetwork6Parser parser;
diff --git a/src/lib/dhcpsrv/tests/shared_network_unittest.cc b/src/lib/dhcpsrv/tests/shared_network_unittest.cc
index 58df64673e..aefe3bc398 100644
--- a/src/lib/dhcpsrv/tests/shared_network_unittest.cc
+++ b/src/lib/dhcpsrv/tests/shared_network_unittest.cc
@@ -1,4 +1,4 @@
-// Copyright (C) 2017 Internet Systems Consortium, Inc. ("ISC")
+// Copyright (C) 2017-2018 Internet Systems Consortium, Inc. ("ISC")
 //
 // This Source Code Form is subject to the terms of the Mozilla Public
 // License, v. 2.0. If a copy of the MPL was not distributed with this
@@ -195,7 +195,7 @@ TEST(SharedNetwork4Test, unparse) {
     network->setValid(200);
     network->setMatchClientId(false);
 
-    network->deferClientClass("foo");
+    network->requireClientClass("foo");
 
     // Add several subnets.
     Subnet4Ptr subnet1(new Subnet4(IOAddress("10.0.0.0"), 8, 10, 20, 30,
@@ -258,7 +258,7 @@ TEST(SharedNetwork4Test, unparse) {
         "        \"valid-lifetime\": 30\n"
         "      }\n"
         "    ],\n"
-        "    \"eval-client-classes\": [ \"foo\" ],\n"
+        "    \"required-client-classes\": [ \"foo\" ],\n"
         "    \"valid-lifetime\": 200\n"
         "}\n";
 
@@ -482,7 +482,7 @@ TEST(SharedNetwork6Test, unparse) {
     network->setPreferred(200);
     network->setValid(300);
     network->setRapidCommit(true);
-    network->deferClientClass("foo");
+    network->requireClientClass("foo");
 
     // Add several subnets.
     Subnet6Ptr subnet1(new Subnet6(IOAddress("2001:db8:1::"), 64, 10, 20, 30,
@@ -538,7 +538,7 @@ TEST(SharedNetwork6Test, unparse) {
         "        \"valid-lifetime\": 40\n"
         "      }\n"
         "    ],\n"
-        "    \"eval-client-classes\": [ \"foo\" ],\n"
+        "    \"required-client-classes\": [ \"foo\" ],\n"
         "    \"valid-lifetime\": 300\n"
         "}\n";