Our db server is going to change IP address. I changed the DB server IP in Site Admin under DB Server tab.

They changed IP and I tried login in but I couldn't.
So my question is
1.What could be the reason? Was I suppose to put the IP info elsewhere.
2. If your DB server is down and you want to change it where else can you change it since you can't login to QC to change it. Is there a way to change it without login in?