Question 79 of 530 from exam 400-251: CCIE Security written exam

Question 79 of 530 from exam 400-251: CCIE Security written exam


Which IPv6 tunnel type is a standard that is defined in RFC 4214?



A. B. C. D.


The correct answer is A. ISATAP.

ISATAP (Intra-Site Automatic Tunnel Addressing Protocol) is a tunneling protocol used to transmit IPv6 packets over an IPv4 infrastructure. It is designed to enable IPv6 connectivity between IPv6-enabled hosts that are on separate IPv4 networks, without requiring any additional infrastructure.

ISATAP is defined in RFC 4214, which describes the protocol and its specifications in detail. According to RFC 4214, ISATAP is a method of automatically assigning IPv6 addresses to nodes on an IPv4 network, using the MAC address of the node to create a unique interface identifier (IID).

6to4 and GREv6 are also IPv6 tunneling protocols, but they are not defined in RFC 4214.

6to4 is a mechanism for transmitting IPv6 packets over an IPv4 network using a 6to4 tunnel. This tunnel is established between two IPv6 routers, each with a public IPv4 address. 6to4 is defined in RFC 3056.

GREv6 (Generic Routing Encapsulation for IPv6) is a tunneling protocol that can be used to transport IPv6 packets over an IPv4 network, as well as to encapsulate IPv6 packets within IPv6 packets. It is not a standard defined in an RFC, but rather an Internet Draft that has not been finalized or published as an RFC.

Finally, manually configured tunnels are created by network administrators, rather than being automatically configured. Manually configured tunnels can be used to connect two IPv6 networks over an IPv4 network, but they are not a standard tunnel type defined in an RFC.