It is also more scalable and much easier to manage. A single Authentication Server can support hundreds of communications servers, serving up to tens of thousand of users. Communications servers can access an Authentication Server locally or remotely over WAN connections. Authentication Servers can be set up in a variety of ways, depending upon the security scheme of the network they are serving. Passwords are the most common form of computer security.
Some networks require multiple levels of passwords to gain access to various servers or databases.
Passwords become weak links when they are shared among colleagues, stolen, written down or created in such a way that they can be easily guessed. For example, users will try to create memorable passwords by using their names or social security numbers. Callback provides good security and cost savings to users who remotely access networks from one location. However, it is inconvenient for traveling executives. Packet filters allow network administrators to limit a user's access to specific services on the network.