DNS is essential to the operation of the mesh.  Ideally, you should never have to know the IP address of any mesh node, just its hostname.  Every node functions as a DNS server, and it receives updates from the other nodes on the mesh so it knows what other node names are available.  For DNS to work at all it needs to work within a domain, and that domain is austin.tx.us.mesh.

The mesh is unlike most other networks in that it does not have or require any centralized administration.  The network configures itself.  Getting DNS to work correctly in this environment is a very complex problem, one that is not yet solved and will not be for some time.  Even though the domain name will not match your region unless you are in Austin, at this time it really does not matter what it is, and changing it only provides an opportunity to break the network.  For the most part you can ignore it.  The installed mesh infrastructure is not yet anywhere near the size where separate domains are needed.  So for now, just bear with it until the mesh matures and complex underlying issues are worked out.