What are TACACS (Terminal Access Controller Access Control System) and RADIUS (Remote Authentication Dial In User Service) in networking?

What are TACACS (Terminal Access Controller Access Control System) and

1.	What are TACACS (Terminal Access Controller Access Control System) and RADIUS (Remote Authentication Dial In User Service) in networking?
Answer» TACACS: It is a group of remote AUTHENTICATION protocols useful in controlling remote authentication and other related services for the networked access control via a centralized server. TACACS will HELP for determining whether the user is having access to the network or not as it will permit the remote access server to communicate with an authentication server. RADIUS: It is an AAA (Authentication, Authorization, and ACCOUNTING) protocol to control access to network resources. RADIUS is used by ISPs (Internet Service Providers) and corporations to manage access into the Internet or internal networks across a group of access technologies that INCLUDE wireless, DSL, modem, and VPNs.