diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index 32c240e4ca..48171cc19b 100644
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -8980,7 +8980,7 @@ avoid-v6-udp-ports { 40000; range 50000 60000; };
 	      <term><command>edns-udp-size</command></term>
 	      <listitem>
 		<para>
-		  Sets the initial advertised EDNS UDP buffer size in
+		  Sets the maximum advertised EDNS UDP buffer size in
 		  bytes, to control the size of packets received from
 		  authoritative servers in response to recursive queries.
 		  Valid values are 512 to 4096 (values outside this range
@@ -10639,7 +10639,15 @@ example.com                 CNAME   rpz-tcp-only.
 	    is useful when you wish to advertise a different value
 	    to this server than the value you advertise globally,
 	    for example, when there is a firewall at the remote
-	    site that is blocking large replies.
+	    site that is blocking large replies. (Note: Currently,
+	    this sets a single UDP size for all packets sent to the
+	    server; <command>named</command> will not deviate from
+	    this value.  This differs from the behavior of
+	    <command>edns-udp-size</command> in <command>options</command>
+	    or <command>view</command> statements, where it specifies
+	    a maximum value. The <command>server</command> statement
+	    behavior may be brought into conformance with the
+	    <command>options/view</command> behavior in future releases.)
 	  </para>
 
 	  <para>