Why do hostnames continue to be logged after DNS lookups are disabled?

For performance reasons, the web server initiates an asynchronous DNS reverse-lookup of the client's IP address before it has parsed the HTTP "Host:" header, which is used to determine the virtual server that should handle the request. Therefore, turning on DNS lookups for any virtual server actually enables DNS lookups for all virtual servers.

If you wish to disable DNS lookups entirely, you should ensure that they are turned off for all virtual servers.

The tunable 'dnslookup' in the virtual server configuration files determines whether or not reverse lookups will occur. Set it to 'no' to disable lookups.

Content Manager [Administrator] 19 September 2005