[3740] Small update to the User Guide (DHCPINFORM)

diff --git a/doc/guide/dhcp4-srv.xml b/doc/guide/dhcp4-srv.xml
index b355c630653c02c042c5b22403cb2a56abf08684..f61c49bb4f10f87e7fb6982e4bdfe034a4ff4ccf 100644 (file)
--- a/doc/guide/dhcp4-srv.xml
+++ b/doc/guide/dhcp4-srv.xml
@@ -590,9 +590,10 @@ temporarily override a list of interface names and listen on all interfaces.
   relies on the low level functions of an operating system to build the
   data link, IP and UDP layer of the outgoing message. Typically, the
   OS will first use ARP to obtain the client's link layer address to be
-  inserted into the frame's header. When the ARP exchange is successful,
-  the DHCP message can be unicast to the client, using the address
-  obtained.
+  inserted into the frame's header, if the address is not cached from
+  the previous transaction that the client had with the server.
+  When the ARP exchange is successful, the DHCP message can be unicast
+  to the client, using the address obtained.
   </para>
 
   <para>Some system administrators block ARP messages in their network,