Timeout for resolver

Barry Margolin barmar at genuity.net
Wed Jul 18 17:58:13 UTC 2001


In article <9j4bdj$bhg at pub3.rc.vix.com>,
Weeber, Burkhard <b.weeber at viastore.de> wrote:
>So my question is how long does it take these days to resolve a
>non-cached record ?

It should normally take at most a few seconds.  If it takes longer, it's
usually due to lame delegations.  DNS queries are retransmitted every few
seconds to deal with packet loss.

>Five minutes aren't enough.

Clients will usually time out in much less than five minutes, so this is
certainly long enough for the firewall to keep the port open.  According to
the table on p.108 of the DNS&BIND book, the total length of the BIND
resolver timeout (after all retries are performed, and using default retry
settings) is between 75 and 81 seconds, depending on how many nameservers
are listed in the named.conf file.  Other clients may have different
behavior, but they probably won't wait much longer than this.

I don't know offhand what the timeouts are in named itself when it's
performing recursive queries, but it's also not likely to be longer than
this.

>Are the timeouts added up with each forwarder ?

Each forwarder has its own timeouts.  But the client doesn't know how many
levels of forwarding is going on, so it won't increase its timeout to
accomodate this.

-- 
Barry Margolin, barmar at genuity.net
Genuity, 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 group.


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