does a private network's owner have any other capability to identify a connection's IP when a BNC account is used
No.
Does mIRC have any network related settings that will divulge the user's real IP number even if the connection is done through a BNC or Tor
Yes and no.
No, mIRC will never intentionally reveal any IP information about the client connected-- that information is purely held by the server.
However, there are some things that as an IRC client user you should be aware of, and this goes for any client across the board: using DCC functionality on IRC requires a "Direct Connection" from a user to you-- this means revealing some end-point IP address for the remote user to connect to. This may be your BNC/Tor IP, but due to configuration in many IRC clients, this
may be your real IP. Be careful when using DCC over BNC/Tor if privacy is an issue to you.
mIRC allows the user to configure the client to use a specific IP address for DCC requests. It does this via the "Lookup Method" which is found in Alt-O -> Connect -> Local Info. You can also change this via command line with the /localinfo command.
Lookup method should always be set to [x] Server (type /localinfo -u) otherwise you run the risk of having mIRC divulge your IP.
Keep in mind that the /localinfo command may still not leave you completely secure if you use specific BNC software that forwards your real IP for DCC requests. This is usually used to get DCC working over BNC but if privacy is a concern you should check that your BNC software has this feature disabled, if it exists.
The summary is that you should really not worry about mIRC divulging any host information as it stores nearly none (besides what is used for direct connections), but rather your BNC/proxy software. Finally remember that the server only knows the IP address that you connect as with the BNC/Tor host; while the IRC protocol theoretically has a slot in the connection handshake to specify a host, it's rarely used in modern IRCd's-- they usually just go by the IP/hostname of the host machine that initiated the TCP connection to the server and collect/ask for no other host info.
