to get more detail, use 'guardian.cgi'. I forgot where I got it, do a search for it relative to 404 errors. Let me know if you can't find it. It reveals much info about your 404 requests, which revealed to me where the traffic was coming from, allowing me to manipulate my domains useage.
An example, I picked up some old domains that had old sites. The old links were still sending traffic, sometimes from deep directory pages. I was able to set up identical directory/file names and show the surfers specific content, efective for affiliate stuff. I also found some sites trying to show the an old domains logo.gif, (they were stealing am image off of another domain for thier domains homepage) so I gave a copy of my logo the identical file name, and now MY logo shows up on thier page, they have no idea where it is coming from! Funny stuff. Also, it showed me which domains were gettign the old link traffic and which ones were not.
You set your htaccess to go to the guardian.cgi on any type of error you like, 404, 401, 501, etc, and it sends you an email of a report of the hit, or files it for you. It shows the IP, linking url, and the file requested, all the http header stuff you can't get with a quick 404 redirection. And after it sends you the email it THEN does the redirect to your desired 404 catch page, homepage, whatever.
If you have a host/server related error, like 500 series errors, you can set it to mail your host admin to alert them about it automatically while you sleep, if your site goes down they need to hop to it.
Also, you can see when people are poking around your site deep in the directories, stabbing at file names, perhaps hacking around; you got their ip, browser type, host name, etc. if you ever needed it.
More involved that you may have asked for, but very good when that stuff matters, especially when you run a bunch of dropped domains!
Regards.
L Golding
