Source of network_name for distributor So, I have a really weird case.
Was doing a migration from sql server 2005 to 2012. Built the server, and at the last minute we found that the server was called abc/xyz. We just wanted abc, so the DBA did a bunch of stuff including dropping servernames and adding entries to the TCPIP and now we have abc!

Now, I come to creating a publisher. Start by configuring a distributor, and it fails. I get the message that the abc cannot be configured as a distributor because it cannot connect to abc/xyz (old server name) since 'distributor_admin' is not defined as a remote login at the server.

If I do select @@servername, the answer is abc. If I do sp_helpserver I see that a linkedserver has been created to repl_distributor to abc/xyx (old server).

I've tried editing repl_distributor to point to an actual server, but thus far, no success.

Any ideas? I'm totally stuck.
"abc" would be a default instance, where "abc" is the actual server name. Sounds like you created a named instance where /xyz is the name of the instance. This allows you to have multiple instances of SQL Server on the same server. The only way to remove the instance is to uninstall SQL Server and then reinstall with the name you want.