PureMessage for UNIX: How to increase the speed of DNS lookups
PureMessage performance is strongly correlated with the performance of the DNS server, when the Anti-Spam filter is configured to perform DNS lookups (recommended).
What to do
PureMessage performs a variety of DNS checks, including reverse DNS lookups and queries that are handled via the Sophos SXL architecture. For optimal performance, install a local caching DNS server (see http://www.dns.net/dnsrd/servers/ for more information).
Although it is possible to disable network checks completely by setting the local_tests_only option in /opt/pmx/etc/spam.conf to "on", this is not recommended because it will negatively affect catch rates. You can specify the server(s) used for DNS based checks in /opt/pmx/etc/spam.d/net.conf. The net.conf configuration file also allows you set values such as "retry" and "timeout".
If you need more information or guidance, then please contact technical support.
- Article ID: 36620
- Created: 3 Apr 2008
- Last updated: 24 Oct 2008
