DNS name should work as long as it's resolved to ur IP. 7874 for peers, 7875 for client and 7876 for API reqeusts.
I tried setting up a node at nxt.airdns.org, port 7874 is open. But it keeps getting blacklisted (when checking from another instance of Nxt on a different machine). Still trying to figure out why, any ideas? I can't use port 7876 because I am using a VPN with a shared exit IP and port 7876 is already reserved by another user.