I have a couple of servers that I need to remotely monitor. Is there anyway that I can do that? Should I use vncviewer, ssh, or what? 
How can I remotely access linux servers
linux;remote
Most of the time you will use ssh. vncviewer might be available, but often it isn't  (most servers will not have X11 or anything graphics-related). Why use SSH? From the CentOS documentation:After an initial connection, the client can verify that it is connecting to the same server it had connected to previously.The client transmits its authentication information to the server using strong, 128-bit encryption.All data sent and received during a session is transferred using 128-bit encryption, making intercepted transmissions extremely difficult to decrypt and read.The client can forward X11 applications from the server. This technique, called X11 forwarding, provides a secure means to use graphical applications over a network.