diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index 3317efa399..e47420238b 100644
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -6087,6 +6087,35 @@ options {
 	      </listitem>
 	    </varlistentry>
 
+	    <varlistentry>
+	      <term><command>answer-cookie</command></term>
+	      <listitem>
+		<para>
+		  When set to the default value of <userinput>yes</userinput>,
+		  COOKIE EDNS options will be sent when applicable in
+		  replies to client queries. If set to
+		  <userinput>no</userinput>, COOKIE EDNS options will not
+		  be sent in replies.  This can only be set at the global
+		  options level, not per-view.
+		</para>
+		<para>
+		  <command>answer-cookie</command> is only available
+		  as a temporary measure, for use when
+		  <command>named</command> shares an IP address
+		  with other servers that do not yet support DNS
+		  COOKIE.  A mismatch between servers on the same
+		  address is not expected to cause operational
+		  problems, but the option to disable COOKIE responses
+		  so that all servers have the same behavior is
+		  provided out of an abundance of caution. DNS COOKIE
+		  is an important security mechanism and should not be
+		  disabled unless absolutely necessary.  The
+		  <command>answer-cookie</command> option is obsolete
+		  as of BIND 9.13.
+		</para>
+	      </listitem>
+	    </varlistentry>
+
 	    <varlistentry>
 	      <term><command>send-cookie</command></term>
 	      <listitem>