SInce bitnet is not an official TLD you will need to specify the nameserver, since the root won’t forward it.

So, grab a copy with:

 dig IN AXFR bitnet @ns.fsf.net

Note that the old zone file had underscores in the hostnames.  Anywhere you see a dash here, it should be an underscore to be the correct bitnet name.

bit.net is still alive (from the IP address it’s still a machine at Princeton) serving a document explaining the bitnet history.

Adam