Merge branch '2250-dns-flag-day-2020-revert-nocookie-udp-size-v9_11' into 'v9_11'

Resolve "DNS Flag Day 2020 - EDNS buffer size configuring does not work anymore"

See merge request isc-projects/bind9!4457

CHANGES

@@ -1,3 +1,6 @@
+5544.	[func]		Restore the default value of nocookie-udp-size to 4096.
+			[GL #2250]
+
 5541.	[func]		Adjust the "max-recursion-queries" default from 75 to
 			100. [GL #2305]
 

bin/named/config.c

@@ -90,7 +90,7 @@ options {\n\
 	memstatistics-file \"named.memstats\";\n\
 #	multiple-cnames <obsolete>;\n\
 #	named-xfer <obsolete>;\n\
-	nocookie-udp-size 1232;\n\
+	nocookie-udp-size 4096;\n\
 	notify-rate 20;\n\
 	nta-lifetime 3600;\n\
 	nta-recheck 300;\n\

doc/arm/Bv9ARM-book.xml

@@ -6211,8 +6211,9 @@ options {
 		  This sets the maximum size of UDP responses that are
 		  sent to queries without a valid server COOKIE. A value
 		  below 128 is silently raised to 128. The default
-		  value is 1232, but the <command>max-udp-size</command>
-		  option may further limit the response size.
+		  value is 4096, but the <command>max-udp-size</command>
+		  option may further limit the response size as the default
+		  for <command>max-udp-size</command> is 1232.
 		</para>
 	      </listitem>
 	    </varlistentry>

doc/arm/notes-9.11.26.xml

@@ -65,6 +65,18 @@
           #2305]
         </para>
       </listitem>
+      <listitem>
+	<para>
+	  Restore the <command>nocookie-udp-size</command> default from 1232 to
+	  4096. Normally the EDNS buffer size is configured by
+	  <command>max-udp-size</command>, but this configuration option
+	  overrides the value, but most people don't and won't realize there's
+	  an extra configuration option that needs to be tweaked. By changing
+	  the default here, we allow the the <command>max-udp-size</command> to
+	  be the sole option that needs to be changed when operator wants to
+	  change the default EDNS buffer size. [GL #2250]
+	</para>
+      </listitem>
     </itemizedlist>
   </section>