I live in a large apartment building that provides a wireless service for residents. All of that traffic goes through a proxy server, and the domain name on that server contains the name of the apartment building and the city.
So, when I load a "what is my IP" service in my browser, it lists not just the IP I'm connecting from, but also something like "the-ritz-altoona.example.com".
I can see no reason for revealing such information. It's not advertising: who's going to see it? It's of no value to the authorities: they can get the same information directly from the ISP.
However, I can see it of being use to stalkers, criminals responding to Craigslist ads, hackers, identity thieves, and so on.
Am I right to be concerned?
P.S. I use a VPN but that isn't allowed with some sites.