[CentOS] Slow domain resolution problem

[Tom H]

On Mon, Aug 23, 2010 at 9:48 AM, Giles Coochey <giles at coochey.net> wrote:
>
> The problems can sometimes be caused by not having reverse-DNS records for
> your hosts. Can you resolve to names (any name) from an IP address?
> e.g. nslookup 10.2.9.2?

If this is a reverse-lookup problem and you can't have a
reverse-lookup zone (I worked at a company where the Windows admins
refused to create one when we asked them to do so!), you can add
"[NOTFOUND=return]" to the hosts line in nsswitch.conf after "dns"
otherwise your dns server will forward the query out to the net
(assuming that your egress rules allow it to do so) and an answer will
be returned by the some servers set up for this purpose on the net -
called blackhole-something, IIRC.