Add text describing the changes done in the MR in more detail

(cherry picked from commit 096d41b4e266c003cc3e6234c864f0a7d15145ab)
(cherry picked from commit 469286e8eb24ebd6227e65b18eb4c30e13a58877)

diff --git a/CHANGES b/CHANGES
index 61363ae6b30f592e3991e8d87ae2b11cb59e7985..ff82b3743fb066ff3f6b3871c86ab041a982deb2 100644 (file)
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+5516.  [func]          The default EDNS buffer size has been changed from 4096
+                       to 1232. [GL #2183]
+
 5513.  [doc]           The ARM section describing the "rrset-order" statement
                        was rewritten to make it unambiguous and up-to-date with
                        the source code. [GL #2139]

diff --git a/doc/arm/notes-9.11.24.xml b/doc/arm/notes-9.11.24.xml
index c8d0332ef47cf73da020cf080e5c1d8e2a5d770d..dbccba64d9de91d543a3276cf814c6f311325340 100644 (file)
--- a/doc/arm/notes-9.11.24.xml
+++ b/doc/arm/notes-9.11.24.xml
@@ -55,7 +55,16 @@
     <itemizedlist>
       <listitem>
         <para>
-          None.
+         [DNS Flag Day 2020]: The default EDNS buffer size has been changed
+         from 4096 to 1232.  According to the measurements done by multiple
+         parties this should not be causing any operational problems as most of
+         the Internet "core" is able to cope with IP message sizes between
+         1400-1500 bytes, the 1232 size was picked as a conservative minimal
+         number that could be changed by the DNS operator to a estimated path
+         MTU minus the estimated header space. In practice, the smallest MTU
+         witnessed in the operational DNS community is 1500 octets, the
+         Ethernet maximum payload size, so a a useful default for maximum
+         DNS/UDP payload size on reliable networks would be 1400. [GL #2183]
         </para>
       </listitem>
     </itemizedlist>