Dumbpipe is using our set of relays. It is meant as a standalone tool as well as a showcase for what you can do with iroh.

If you use iroh as a library, you can specify your own relays.

It is important to mention that relays are interoperable, so you don't have isolated bubbles of nodes using certain relay networks. I can have the n0 relays specified and still talk to another node that is using a different set of relays.