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Re: DNS cache?
From: |
Jan-Henrik Haukeland |
Subject: |
Re: DNS cache? |
Date: |
Tue, 25 Jan 2005 06:44:42 +0100 |
On Jan 25, 2005, at 0:22, Jonathan Trott wrote:
I am monitoring a remote web cluster using monit. The cluster is
connected
using multiple ADSL connections and the load is distributed using round
robin DNS with a TTL of 0. The problem is that when I test http using
the
DNS name in monit, it appears to cache the DNS response the first time
it
starts up and doesn't refresh the record.
Actually monit does not cache the host name. Each socket connection use
gethostbyname() to lookup the host. However caching can occur in this
function since it use a name server to resolve the host name. Without
picking up my copy of Stevens and investigate this further I have
simply peppered the network code with endhostent() after
gethostbyname() is used. This may or may not fix the problem. Please
check out the monit code from CVS using the instructions here
http://savannah.nongnu.org/cvs/?group=monit and use anonymous access to
checkout.
Please let us know if this fix the problem, otherwise we'll just have
to dig deeper :)
Ps. Also check that your name server really does return different
ip-addresses on lookup.
--
Jan-Henrik Haukeland
Mobil +47 97141255