Re: DNS lookup for git.postgresql.org

On Tue, Jun 29, 2021 at 11:26:54PM -0400, Tom Lane wrote:
> Bruce Momjian <bruce@momjian.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.plline 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@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

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