That's a bit odd. It sounds like your ssh client is having trouble resolving host names when run as a non-root user. What kind of machine (OS and version) are you using as a client? It sounds like some variant of *nix. Can you resolve names otherwise as a non-root user? E.g., can you open a web browser and browse to say, www.google.com
on the client?
One other thought, is servername the actual fully qualified domain name of your server? Did you perhaps define an alias in root's ~/.ssh/config on your client and then try to use that alias from your normal user account? If so, you'll need to add the alias to the normal user account's ~/.ssh/config to use it.