I have an issue with my student computers - they can't connect to the internet.
Here's the weird part: I open a command prompt and ping our gateway server, and suddenly everything is fine (at least for a while). I don't know what the ping is doing to allow the connection to work.
I've tried ipconfig /flushdns and deleting and recreating routes, and it doesn't work. I thought maybe the ping was forcing machines to cache a dns entry, but it doesn't matter if I ping by IP or by dns name. Visiting the gateway server via a web browser also has no effect — a ping is the only thing I've found that helps.
No computers in my lab or admin subnets have this problem; it's just the student machines.s The only other distinguishing factor is that admin/lab machines are joined to our active directory domain, while student machines obviously are not.
Any idea what's going on here? It's got to be something stupid I should have spotted already.