Timeout because of AAAA requests

[Simon Waters]

Peter Gober wrote:
> 
> Now, newer applications (e. g. ssh) seem to do an ipv6 DNS lookup
> (AAAA) first and only then a ipv4 request. If a root server in our
> setup is available, everything works fine: The AAAA request is
> satisfied negatively, the following ipv4 request is answered by our
> name server. But if we "pull the plug" (cut the connection to the root
> servers), the request for the AAAA record timeouts. Unfortunately, it
> didn't help to include a AAAA record of the kind :::FFFF:192.168.1.1;
> in this case ssh complains about an "unknown address family".

This has just been covered in a thread on uk.comp.os.linux

OpenSSH rpm's seems to being shipped with IP6 switched on. You
can force IPv4 only as a command line argument (-4 iirc) or
rebuild from source without IPv6 as workarounds.

I don't think the time out issue when servers are unavailable is
specific to IPv6, just that the IPv6 queries reveal the problem
(as the IPv4 answers are more likely to be cached). Why are your
authoritative servers so rarely available for this to be a
problem? Or did I miss understand? 

I know it bugged me for some reason many moons ago, I think I
had a less than optimal search path in resolv.conf or some such,
so I was issuing multiple AAAA (and A) queries for non-existant
servers before it resolved the correct name.