[evla-sw-discuss] DNS lookups

[Rich Moeser]

James,

I have 2 programs that do frequent DNS lookups. One is responsible for 
loading monitor data into the archive and the other handles alerts. The 
archiver is definitely the bigger problem of the pair because it does 
not cache IP addresses and hostnames. And to make matters worse, I 
currently have two copies of the archiver running, one on mcmonitor and 
the other on mctest. Eventually the copy on mctest will be turned off, 
but it will likely run for several months. The alert handler, also 
running on mcmonitor, will generate lots of lookups at initialization 
and with time should taper off due to caching of the hostnames. I think 
the best solution to this problem is for me to cache the hostnames in 
the archiver.

--Rich

James Robnett wrote:
> 
>    A while back there was a problem with the monitor software
> doing DNS lookups every time a MIB created a monitor point.
> Normally this wouldn't have been a problem except that this
> particular device was generating hundreds of points/second
> which caused hundreds of lookups/second which swamped
> the DNS server.
> 
>    We don't have quite the same issue but while tracking a
> different problem at the site I saw that we have a fairly heavy
> aggregate lookup load going on.
> 
>    Is there a real reason why the monitor software needs to
> know hostnames for every point?   Why can't everything be
> reported and stored as IP addresses and if a human needs
> the hostname do the lookup then.
> 
>    Most systems work this way.
> 
>    Alternatively is there any reason not to use a table (other
> than redundancy of effort) for the hostname/IP pairs on
> mctest/mcmonitor etc?
> 
>     If that's not an option we should consider making those
> systems that really need to do lookups on a frequent basis
> be DNS caching slaves so they have their own table.
> 
> James
> 
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