From ab0bf492035c01687dfff8f546b78ac30739348c Mon Sep 17 00:00:00 2001
From: Mark Andrews <marka@isc.org>
Date: Thu, 26 Nov 2020 15:59:14 +1100
Subject: [PATCH] Adjust default value of "max-recursion-queries"

Since the queries sent towards root and TLD servers are now included in
the count (as a result of the fix for CVE-2020-8616),
"max-recursion-queries" has a higher chance of being exceeded by
non-attack queries.  Increase its default value from 75 to 100.
---
 CHANGES                     | 3 +++
 bin/named/config.c          | 2 +-
 doc/arm/reference.rst       | 2 +-
 doc/notes/notes-current.rst | 6 ++++++
 lib/dns/resolver.c          | 2 +-
 5 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/CHANGES b/CHANGES
index 9d93b66fdd..1b8f964817 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,3 +1,6 @@
+5541.	[func]		Adjust the "max-recursion-queries" default from 75 to
+			100. [GL #2305]
+
 5540.	[port]		Fix building with native PKCS#11 support for AEP Keyper.
 			[GL #2315]
 
diff --git a/bin/named/config.c b/bin/named/config.c
index 9b0c6f06e2..437d92ab5b 100644
--- a/bin/named/config.c
+++ b/bin/named/config.c
@@ -170,7 +170,7 @@ options {\n\
 	max-clients-per-query 100;\n\
 	max-ncache-ttl 10800; /* 3 hours */\n\
 	max-recursion-depth 7;\n\
-	max-recursion-queries 75;\n\
+	max-recursion-queries 100;\n\
 	max-stale-ttl 43200; /* 12 hours */\n\
 	message-compression yes;\n\
 	min-ncache-ttl 0; /* 0 hours */\n\
diff --git a/doc/arm/reference.rst b/doc/arm/reference.rst
index bcbbe3d05d..fd40de3837 100644
--- a/doc/arm/reference.rst
+++ b/doc/arm/reference.rst
@@ -3514,7 +3514,7 @@ Tuning
 ``max-recursion-queries``
    This sets the maximum number of iterative queries that may be sent while
    servicing a recursive query. If more queries are sent, the recursive
-   query is terminated and returns SERVFAIL. The default is 75.
+   query is terminated and returns SERVFAIL. The default is 100.
 
 ``notify-delay``
    This sets the delay, in seconds, between sending sets of NOTIFY messages for a
diff --git a/doc/notes/notes-current.rst b/doc/notes/notes-current.rst
index c58df5cafb..23dae45db3 100644
--- a/doc/notes/notes-current.rst
+++ b/doc/notes/notes-current.rst
@@ -41,6 +41,12 @@ Feature Changes
   configuration. A new option 'nsec3param' can be used to set the desired
   NSEC3 parameters, and will detect collisions when resalting. [GL #1620].
 
+- Adjust the ``max-recursion-queries`` default from 75 to 100. Since the
+  queries sent towards root and TLD servers are now included in the
+  count (as a result of the fix for CVE-2020-8616), ``max-recursion-queries``
+  has a higher chance of being exceeded by non-attack queries, which is the
+  main reason for increasing its default value. [GL #2305]
+
 Bug Fixes
 ~~~~~~~~~
 
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index fcfbae17c6..447d85062b 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -181,7 +181,7 @@
 
 /* The default maximum number of iterative queries to allow before giving up. */
 #ifndef DEFAULT_MAX_QUERIES
-#define DEFAULT_MAX_QUERIES 75
+#define DEFAULT_MAX_QUERIES 100
 #endif /* ifndef DEFAULT_MAX_QUERIES */
 
 /*