Argus Tip #882 - The Asynchronous Resolver
jaw+arguslist at tcp4me.com
Sat Jan 29 13:27:14 EST 2005
What is this "asynchronous resolver" thing?
normally, when argus starts, it uses your systems standard
"gethostbyname()" function to do DNS lookups to convert
hostnames (mail.example.com) in your config to their
IP address (192.168.1.2).
the asynchronous resolver is a replacement DNS resolver
that argus can use instead of the standard gethostbyname().
argus runs it continuously in the background.
Why would I want to do that?
if you are monitoring a large number of hosts, doing a lot of
DNS lookups one at a time, can cause argus to take a long
time to start up. with the asynchronous resolver enabled,
argus doesn't have to wait for the DNS lookups, and can start
up faster while multiple lookups happen in the background.
and, normally, argus only does the DNS lookups at start time;
with the asynchronous resolver enabled, argus will periodically
re-look things up every so often, so you can change the IP
address of a server and argus will switch to the new address
without needing to reload.
How do I enable it?
in you config file, after your top level data definitions,
and before your first Group or Service, add:
# various parameters
unless you specify otherwise, argus will fetch the needed
parameters from your /etc/resolv.conf file
this is only available in the development code
if your resolv.conf specifies multiple search domains
only one will be used
if your resolv.conf contains anything wacky, argus
probably won't understand it
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