I agree with your sentiment.<p>My first thought, however, was that is extremely costly to dynamically lookup DNS for every page request. Even if a DNS lookup was only performed if the IP matched that range, you'd still end up doing a DNS lookup for every MSNBot hit. If they're calling way too many pages (which is the reason for the block in the first place), this will thrash your server.<p>Now, if you followed the above but then added the IP to a static blacklist if it resolved to an MSFT host - and a whitelist if not - then the system should work without too much of a performance hit (except a small one upfront).<p>Of course, at that rate, it would probably be easier to just submit a batch job to generate IPs in that range for blacklist and whitelist.<p>Anyways, your rhetorical point still stands :-)