remove discussion about falling back to plain DNS on timeout

diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index 86d4ccd187676d86f40b624930cdfdad8f5270c7..f1722e104cfb9953eb9e41bd2b17a969cbd9e4ff 100644 (file)
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -8963,18 +8963,7 @@ avoid-v6-udp-ports { 40000; range 50000 60000; };
                  this has the greatest chance of success on the first try.
                </para>
                <para>
-                 If the initial response times out, <command>named</command>
-                 will try again with plain DNS, and if that is successful,
-                 it will be taken as evidence that the server does not
-                 support EDNS. After enough failures using EDNS and
-                 successes using plain DNS, <command>named</command>
-                 will default to plain DNS for future communications
-                 with that server.  (Periodically, <command>named</command>
-                 will send an EDNS query to see if the situation has
-                 improved.)
-               </para>
-               <para>
-                 However, if the initial query is successful with
+                 If the initial query is successful with
                  EDNS advertising a buffer size of 512, then
                  <command>named</command> will advertise progressively
                  larger buffer sizes on successive queries, until