minor tangent: source of queries

[Kevin Darcy]

NES has the ability to cache DNS entries (up to 32,768 entries), as well as
to multi-thread lookups. I have no idea why your web admins would turn on
DNS resolution (which is off by default) and *not* turn on local caching in
the webserver. The on-line documentation makes it very clear that this will
hurt the webserver's performance. In fact, having the "DNS" option turned on
in NES is of limited usefulness anyway -- it's only used for putting
hostnames instead of IP addresses into the logfiles, and for restricting
access by hostname (but that's not very secure of course).

Or, maybe it's a very busy webserver and exceeded its cache size? If that's
so, then they should probably be running a local caching nameserver on the
box (and *not* nscd!).


- Kevin

Ian Watts wrote:

> While inspecting the traffic on my busiest nameserver, I discovered that
> one busy webserver in the same facility was regularly hitting the
> nameserver with up to 45 identical queries in a span of 40 ms.  This box
> accounts for about 25-55% of all queries to the nameserver.
>
> So my question is whether or not people may have already identified likely
> software problems/issues that could account for this.  In my case, it's a
> web server running (gasp!) Netscape Enterprise Server 3.62. I don't
> control that box and I can't access it, but I'd like to be able to tell
> the people who DO control it how they can significantly reduce nameserver
> activity as well as network traffic in general.
>
> These query blasts are always for PTR records.  The web server is an E250
> running some version of Solaris.  The nameserver averages about 200-450
> queries per second.
>
> Anyone have any suggestions?  Is this perfectly normal?
>
> TIA,
>
> -- Ian Watts