AAA server is having three processes Authentication, Authorization, and Accounting. AAA server is the most popular thing of the security. It helps the network to become more secure by another. Authentication means the used username and password to become an authenticator. Authorization that authenticator can use the service and so on depending on that the server is given. Accounting that they know what users do and from which website open it is listed from each user. The critical server of AAA Server is RADIUS and TACACS. The AAA server is handy for WLAN and wire.