[PATCH] resolv: Document RES_NOAAAA and no-aaaa stub resolver options

[PATCH] resolv: Document RES_NOAAAA and no-aaaa stub resolver options

[Florian Weimer]

Signed-off-by: Florian Weimer <fweimer@redhat.com>

---
 man3/resolver.3    |  8 ++++++++
 man5/resolv.conf.5 | 15 +++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/man3/resolver.3 b/man3/resolver.3
index fa3e7971d..489b1e231 100644
--- a/man3/resolver.3
+++ b/man3/resolver.3
@@ -407,6 +407,14 @@ This option implies
 .B RES_NOTLDQUERY
 Do not look up unqualified name as a top-level domain (TLD).
 .TP
+.B RES_NOAAAA
+Suppress queries for AAAA (IPv6 address) records.  See the description
+of the
+.B no-aaaa
+option in
+.BR resolv.conf (5)
+for details.
+.TP
 .B RES_DEFAULT
 Default option which implies:
 .BR RES_RECURSE ,
diff --git a/man5/resolv.conf.5 b/man5/resolv.conf.5
index 81ed51b98..a0638bd85 100644
--- a/man5/resolv.conf.5
+++ b/man5/resolv.conf.5
@@ -349,6 +349,21 @@ option has been set correctly.
 In glibc version 2.30 and earlier,
 the AD is not set automatically in queries,
 and is passed through unchanged to applications in responses.
+.TP
+.BR no\-aaaa " (since glibc 2.35)"
+.\" glibc commit f282cdbe7f436c75864e5640a409a10485e9abb2
+Sets
+.B RES_NOAAAA
+in
+.IR _res.options .
+This option disables outgoing AAAA (IPv6 address) queries in the stub
+resolver.  If necessary, AAAA queries are translated into A queries,
+to probe for the existence of host names.  (This preserves different
+error results for missing address data and hosts that do not exist.)
+This option is intended for diagnosing name resolution problems and to
+verify that automatic AAAA queries do not contribute to any DNS
+issues.  If the system has configured any IPv6 name servers, they can
+still be used even if this option is active.
 .RE
 .PP
 The \fIsearch\fP keyword of a system's \fIresolv.conf\fP file can be