#998211 libc6: MAXNS should be increased to allow for redundant IPv6 nameservers

Package:
libc6
Source:
glibc
Description:
GNU C Library: Shared libraries
Submitter:
Daniel Gröber
Date:
2021-12-04 21:39:05 UTC
Severity:
minor
Tags:
#998211#5
Date:
2021-11-01 04:50:15 UTC
From:
To:
Dear Maintainer,

glibc currently limits the number of nameserver directives in
resolv.conf to 3. On IPv4/6 dual-stack hosts this can be quite
limiting. When redundant nameservers are available we can either
choose to have redundancy on v4 or v6 which is unsatisfying.

I'm not aware of this problem having been discussed in Debian before,
but Ubuntu has an open bug[1] for it. There also is a surprisingly
insightful Stackoverflow post[2] on how one might go about increasing
MAXNS without an ABI break.

[1]: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/118930
[2]: https://stackoverflow.com/questions/64047757/more-than-3-dns-server-in-ubuntu
#998211#10
Date:
2021-12-04 21:34:00 UTC
From:
To:
control: severity -1 minor

As you pointed out changing MAXNS would cause an ABI break. The proposal
you pointed out looks like a good way to do the change, but it needs to
be done upstream in order to keep a compatible ABI between all
distributions.

In the meantime using a local resolver like unbound is the best
workaround.