can we disable AAAA queries in the resolver ?

Luigi Rizzo rizzo at
Fri Aug 1 23:52:07 PDT 2003

recently i have been bitten by a problem which might be already
known, but still...

quite a few apps (sendmail and ssh among them) seem to always
try an AAAA query if compiled with ipv6 support, and even if
the kernel does not support ipv6, tcpdump shows AAAA queries going out
to the nameserver, and often timing out or otherwise causing my
apps significand delays at startup.

My understanding is that there are multiple buggy components here:
my ISP's nameserver certainly shouldn't behave so badly on AAAA
requests, and the applications should not bother asking AAAA queries
when the kernel has no ipv6 support.
On the other hand, the resolver code is probably just innocent
because if some application issues an AAAA request, the resolver
has no reason to object. Still, rather than fixing the many
broken applications, or the nameserver (on which i have no control)
i wonder if it is possible to instruct the resolver, perhaps through
some option in resolv.conf, to immediately return some kind
of negative replies on selected queries ?


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