How Google knows you're using AOL?

I assume that you've not signed up to AOL, so they can't be doing a reverse lookup on the location of your IP address. Unless, of course, AOL uses proxy servers which, come to think of it, I'm pretty sure it does. (Sorry – I'm thinking as I type!)

If this is the case, is it not possible to just use AOL's proxy servers with IE or Firefox?

If this isn't the case, how else could they know? Surely they're not looking at your user agent string – in which case you'd be able to just modify it (or use one of the many applications available for Firefox that do this for you).

Just wondering.

I think it's the US proxy servers indeed. But the AOL client has to authenticate with my AOL screen name, I'm sure. One thing I find strange though is that I couldn't get Google Video playback to work even with some free US-based proxy servers I tried.

yeah, aol uses proxies. our school has a stupid sonicwall, so i've heard of a couple of people who sacraficed thier dignity to have no firewall.