

It doesn’t use a browser, nor DNS https://en.wikipedia.org/wiki/Bitmessage.
It broadcasts all messages, but only the intended recipient can read the message with their private key. So in terms of metadata, they can’t even see who is contacting who. All the third parties know, afaik, is that you use it. They don’t even know when and to or from whom messages are send.
Tcp/ip yes, p2p like bittorrent. You need the address of one peer, who then sends you a list of peers they know, etc.