I have an apache rewrite rule to display a 404 page. It works quite well when someone attempts to access a sub-domain which does not exist or if they enter my ip in the browser address bar.

The rewrite log typically shows the domain they were attempting to access, some session info and the actual rewrite rule playing out.

Now and again I will see a domain name in the log which is in no way associated with my ip. How is it possible that DNS is sending them my way?

Either somebody is deliberately sending those requests your way, or the nameservers responsible for those domains are misconfigured. Why don't you check out those domains yourself?

http://www.kloth.net/services/nslookup.php

DNS may not be involved at all. The domain Apache uses is from the HTTP 'Host' header. A client can connect to an IP and send a Host header saying whatever the hell it wants.

A lot of bots scan for open proxies by making an HTTP request for a website. As long as you aren't running an open proxy, it's best to just ignore them. You could email their abuse@ addresses if you wanted to, I suppose, but...

_________________
Matt Nordhoff (aka Peng on IRC)