[master] clarify message-compression doc

- mention TCP and RFC compliance issues

diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index b7e268bd0985cd9a57d2c1ed53f91c9db4b40cd5..01a7041a10bf1a5b45b1ffc0975ee60679b02981 100644 (file)
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -6154,12 +6154,15 @@ options {
            <varlistentry>
              <term><command>message-compression</command></term> <listitem>
                <para>
-                 If <userinput>yes</userinput>, DNS name compression will
-                 be used for responses to regular queries (not including
+                 If <userinput>yes</userinput>, DNS name compression is
+                 used in responses to regular queries (not including
                  AXFR or IXFR, which always uses compression).  Setting
-                 this option to <userinput>no</userinput> can result in
-                 larger responses, but will reduce CPU usage on servers.
-                 The default is <userinput>yes</userinput>.
+                 this option to <userinput>no</userinput> reduces CPU
+                 usage on servers and may improve throughput.  However,
+                 it increases response size, which may cause more queries
+                 to be processed using TCP; a server with compression
+                 disabled is out of compiance with RFC 1123 Section
+                 6.1.3.2. The default is <userinput>yes</userinput>.
                </para>
              </listitem>
            </varlistentry>
@@ -6699,7 +6702,7 @@ options {
            <varlistentry>
              <term><command>auto-dnssec</command></term>
              <listitem>
-               <para>
+               <para>
                  Zones configured for dynamic DNS may use this
                  option to allow varying levels of automatic DNSSEC key
                  management. There are three possible settings: