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Bug 2096189 - glibc: Backport no-aaaa resolver option to suppress DNS AAAA queries [rhel-8.7.0]
Summary: glibc: Backport no-aaaa resolver option to suppress DNS AAAA queries [rhel-8....
Alias: None
Product: Red Hat Enterprise Linux 8
Classification: Red Hat
Component: glibc
Version: 8.7
Hardware: Unspecified
OS: Unspecified
Target Milestone: rc
: ---
Assignee: Florian Weimer
QA Contact: Martin Coufal
Petr Hybl
Depends On: 2096191
TreeView+ depends on / blocked
Reported: 2022-06-13 08:45 UTC by Florian Weimer
Modified: 2023-07-18 14:30 UTC (History)
14 users (show)

Fixed In Version: glibc-2.28-207.el8
Doc Type: Enhancement
Doc Text:
.DNS stub resolver option now supports `no-aaaa` option With this enhancement, `glibc` now recognizes the `no-aaaa` stub resolver option in `/etc/resolv.conf` and the `RES_OPTIONS` environment variable. When this option is active, no AAAA queries will be sent over the network. System administrators can disable AAAA DNS lookups for diagnostic purposes, such as ruling out that the superfluous lookups on IPv4-only networks do not contribute to DNS issues.
Clone Of:
: 2096191 (view as bug list)
Last Closed: 2022-11-08 10:43:12 UTC
Type: Enhancement
Target Upstream Version:

Attachments (Terms of Use)

System ID Private Priority Status Summary Last Updated
Red Hat Bugzilla 1027452 1 high CLOSED glibc: [RFE] Provide mechanism to disable AAAA queries when using AF_UNSPEC on IPv4-only configurations. 2023-12-20 12:07:15 UTC
Red Hat Bugzilla 2096191 1 unspecified CLOSED glibc: Backport no-aaaa resolver option to suppress DNS AAAA queries [rhel-9.1.0] 2023-07-18 14:29:19 UTC
Red Hat Issue Tracker RHELPLAN-125072 0 None None None 2022-06-13 08:48:04 UTC
Red Hat Product Errata RHBA-2022:7684 0 None None None 2022-11-08 10:43:40 UTC

Internal Links: 1027452 2096191

Description Florian Weimer 2022-06-13 08:45:49 UTC
We are working upstream on a no-aaaa stub resolver option that suppresses DNS AAAA queries for diagnostic purposes.

Upstream NEWS entry:

+* The “no-aaaa” DNS stub resolver option has been added.  System
+  administrators can use it to suppress AAAA queries made by the stub
+  resolver, including AAAA lookups triggered by NSS-based interfaces
+  such as getaddrinfo.  Only DNS lookups are affected: IPv6 data in
+  /etc/hosts is still used, getaddrinfo with AI_PASSIVE will still
+  produce IPv6 addresses, and configured IPv6 name servers are still
+  used.  To produce correct Name Error (NXDOMAIN) results, AAAA queries
+  are translated to A queries.  The new resolver option is intended
+  preliminary for diagnostic purposes, to rule out that AAAA DNS queries
+  have adverse impact.  It is incompatible with EDNS0 usage and DNSSEC
+  validation by applications.


[PATCH v2 2/2] resolv: Implement no-aaaa stub resolver option

The proposed patch does not directly affect AF_UNSPEC queries, so it is distinct from bug 1027452, which is why I'm filing a separate bug.

Note to QE: Various “getent” queries (hosts, ahosts, ahostsv4, ahostsv6) for hosts in DNS are expected not to show any AAAA queries in tcpdump if the no-aaaa option is active.

Comment 12 errata-xmlrpc 2022-11-08 10:43:12 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (glibc bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.


Comment 15 Florian Weimer 2022-11-21 11:09:40 UTC
NetworkManager integration is currently missing. If NetworkManager is used to manage /etc/resolv.conf, changes to this file will be overwritten. NetworkManager does not propagate no-aaaa from the interface DNS configuration even if it set there.

Comment 16 Thomas Haller 2023-03-08 14:27:39 UTC
(In reply to Florian Weimer from comment #15)
> NetworkManager integration is currently missing.

FYI: reported as bug 2144521.

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