[cvsnt] Re: CVSNT 41a >10 secs delay with Reverse DNS disabled - any ideas
jpeacock at rowman.com
Wed Jul 21 16:54:27 BST 2004
Tony Hoyle wrote:
> btw. you won't get the delay if your DNS server simply refuses to serve
> the x.y.z.in-addr.arpa domain...
Sorry, you are mistaken here. If the internal DNS server thought it was
authoritative for a zone, yet had no record for a given query, it would
immediately return NXDOMAIN.
The real cause for slowdowns is if the local server is *not*
authoritative, and the domain in question is one of the RFC-1918 ranges
(192.168, 172.16, 10.0), in which case the resolver will eventually get
to the blackhole servers (set up for exactly this purpose) which will
eventually return NXDOMAIN instead. This is what is usually the cause
of reverse DNS timeouts.
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