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Examining the server logs yourself probably wont help your understanding of the issue unless you know what your looking at specifically. On the Yahoo note, i have found Slurp to be really bad in the past, but no legitimate bot should be able to bring down a properly configured web server, especially an 'enterprise-level' one. I would check your .htaccess and apache settings for bad redirects (or web.conf if on windows) before considering banning the bot. Other things to check would be website code or if a bot hits a massive and horribly optimised Database Query for example, that could bring the server down. Ask IT exactly what the bot did that caused the server to go down, they should atleast be able to tell you that. If not then they need to run load tests against the website itself to try and reproduce the scenario and thus debug the issue, if indeed there is one. Tl;dr :- Normally bad config or code / queries are to blame for this kind of thing. I'd review that before blocking a bot that crawls hundreds of thousands of other sites without issue.