802.1x is an IEEE Standard for port-based Network Access Control (PNAC). It is part of the IEEE 802.1 group of networking protocols. It provides an authentication mechanism to devices wishing to attach to a LAN.
TACACS+ is an AAA protocol developed by Cisco. TACACS+ separates the authentication, authorization, and accounting steps. This architecture allows for separate authentication solutions while still using TACACS+ for authorization and accounting. For example, it is possible to use the Kerberos Protocol for authentication and TACACS+ for authorization and accounting. After an AAA client passes authentication through a Kerberos server, the AAA client requests authorization information from a TACACS+ server without the necessity to re-authenticate the AAA client by using the TACACS+ authentication mechanism.
Authentication and authorization are not separated in a RADIUS transaction. When the authentication request is sent to a AAA server, the AAA client expects to have the authorization result sent back in reply.
It is a waste to administratively shut down the interface. Moreover, someone can still access the virtual terminal interfaces via other interfaces -> A is not correct.
We can not physically secure a virtual interface because it is “virtual” -> B is not correct.
To apply an access list to a virtual terminal interface we must use the “access-class” command. The “access-group” command is only used to apply an access list to a physical interface -> C is not correct; E is correct.
The most simple way to secure the virtual terminal interface is to configure a username & password to prevent unauthorized login -> D is correct.
One of the most widely deployed network security technologies today is IPsec over VPNs. It provides high levels of security through encryption and authentication, protecting data from unauthorized access.