Accept, Accept-Encoding and similar pitfalls

[Connor Walls]

Hi,

I know this isn't specifically a varnish issue, but I imagine it's a problem that many people here have faced, and might be able to give some help with. Recently we had an issue where our varnish server was serving up mobile content to desktop users, which was causing a "Save As" dialog whenever a user tried to browse to the homepage. We realised that our backend server was responding with a "Vary: Accept-Encoding" header, but no vary for "Accept", and we've since fixed this problem. 

I'm just curious to find out if there are any other headers that anyone has experienced similar problems with? We're now explicitly dealing with Accept, Accept-Encoding, and deliberately ignoring User-Agent, but is there anything else we should be looking out for?

Thanks,
Connor Walls