Re: DNS lookup for git.postgresql.org

On Tue, Jun 29, 2021 at 11:26:54PM -0400, Tom Lane wrote:
> Bruce Momjian <bruce(at)momjian(dot)us> writes:
> > I have an automated job that pulls from our public git server, and
> > several times a day I get this error:
> > fatal: unable to look up git.postgresql.org (port 9418)
> > (Temporary failure in name resolution)
> > I don't see this error for any of my other automated scripts that pull
> > from URLs. Is this something other people see too? Is it a problem on
> > my end? My git config entry is:
>
> My buildfarm animals frequently complain of being unable to contact the
> buildfarm server. Sometimes there's an identifiable problem at my end,
> but usually not. A typical error looks like
>
> error getting branches of interest: 500 Can't connect to buildfarm.postgresql.org:443 (Network is unreachable) at ./run_branches.pl line 199.
>
> I've not noticed instability of connections to the git servers, though.

OK, thanks. When no one said they saw similar behavior, I started
digging deeper. It seems on Debian 10, bind/named uses IPv6 by default,
and my ISP, Verison FIOS, doesn't support IPv6 yet; see:

https://www.reddit.com/r/Fios/comments/li4ri7/does_fios_support_ipv6/

I also failed this test:

http://test-ipv6.com/

Turns out I had a number of failures for other domains as well, so it
wasn't only git.postgresql.org. I disabled IPv6 by modifying
/etc/default/bind9:

https://serverfault.com/questions/833270/why-am-i-seeing-ipv6-resolve-errors-despite-having-disabled-ipv6-in-bind

Anyway, I am attaching my compressed bind/named debug logs, in case it
is helpful to anyone.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

If only the physical world exists, free will is an illusion.