DNS query timeouts

[Mark_Andrews at isc.org]

> In article <7mkht1$c4b$1 at oravannahka.Helsinki.FI>,
> Tero A Kauppinen  <takauppi at cc.helsinki.fi> wrote:
> >We are currently using FreeBSD 3.2 & Bind 8.1.2 and are 
> >facing some problems when trying to resolve addresses. The setup we 
> >have is as follows:
> >
> >   H -------- S ---------------- B -------- ( The Internet ) ---- X
> > (host) (internal server)   (bastion host)                     (target host)
> >
> >If H tries to query the address of host X, the operation fails for the
> >first time. The problem, as I understand it, is with timing, i.e. S 
> >doesn't wait long enough for an answer from B. However, when the query 
> >is repeated, S has already got an answer for its previous query, and 
> >thus the answer can be found in the cache. 
> >
> >How can I increase the time S waits for an answer from B before
> >returning an error to H?
> 
> I assume S is configured as a forwarding server, with:
> 
>    forwarders { <address of B>; }
> 
> The trick is to put B's address in there multiple times, i.e.
> 
>    forwarders { <address of B>; <address of B>; }
> 
> After S times out on the first address it will try again using the second
> address.
> 
> This worked in BIND 4; I hope they haven't added duplicate detection in
> BIND 8, thinking that it would be an optimization.
> 
> -- 
> Barry Margolin, barmar at bbnplanet.com
> GTE Internetworking, Powered by BBN, Burlington, MA
> *** DON'T SEND TECHNICAL QUESTIONS DIRECTLY TO ME, post them to newsgroups.
> Please DON'T copy followups to me -- I'll assume it wasn't posted to the grou
> p.
> 
> 
	BIND 8.2.1 will try multiple times by default.  The mechanism is
	the same as is used for normal nameservers rather than the linked
	list of old servers.  BIND 8.2.1 has duplicate detection for
	forwarders.

	Mark
--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org