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

(cherry picked from commit 096d41b4e266c003cc3e6234c864f0a7d15145ab)

diff --git a/CHANGES b/CHANGES
index a09f0aa4b4601b5c4a5279a3481bbca1bb1dcb62..2f875887b8c22d66d8b101dc2a35904d22ee94d0 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]
+
 5515.  [func]          Add 'rndc dnssec -rollover' command to trigger a
                        manual rollover for a specific key. [GL #1749]
 

diff --git a/doc/notes/notes-current.rst b/doc/notes/notes-current.rst
index 361a74626934cbe15d0418ed5fdbb74cb9f7f588..462dc0f422f31d34bd329a85a9fcca4cf23aae44 100644 (file)
--- a/doc/notes/notes-current.rst
+++ b/doc/notes/notes-current.rst
@@ -24,8 +24,6 @@ Known Issues
 New Features
 ~~~~~~~~~~~~
 
-- None.
-
 - Add a new ``rndc`` command, ``rndc dnssec -rollover``, which triggers
   a manual rollover for a specific key. [GL #1749]
 
@@ -42,7 +40,15 @@ Removed Features
 Feature Changes
 ~~~~~~~~~~~~~~~
 
-- 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]
 
 Bug Fixes
 ~~~~~~~~~