Refer to the exhibit.
 
The 6to4 overlay tunnel configuration has been applied on each router to join isolated IPv6 networks over a IPv4 network.
Which statements regarding the 6to4 overlay tunnel is true?

A. The least significant 32 bits in the address referenced by the ipv6 route 2002::/16 Tunnel0 command will correspond to the interface E0/0 IPv4 address

B. The least significant 32 bits in the address referenced by the ipv6 route 2002::/16 Tunnel0 command will correspond to the IPv4 address assigned to the tunnel source

C. The configuration is invalid since the tunnel source command must be configured with an IPv6 address

D. This is actually a configuration example of an IPv4-compatible tunnel and not a 6to4 tunnel

E. This is actually a configuration example of an ISATAP overlay tunnel and not a 6to4 tunnel






 

Suggested Answer: B

6to4 tunnels use IPv6 addresses that concatenate 2002::/16 with the 32-bit IPv4 address of the edge router, creating a 48-bit prefix.
The tunnel interface on R1 has an IPv6 prefix of 2002:4065:4001:1::/64, where 4065:4001 is the hexadecimal equivalent of 64.101.64.1, the IPv4 address of its interface in the IPv4 network.
The tunnel interface on R2 has an IPv6 prefix of 2002:4065:4101:1::/64, where 4065:4101 is the hexadecimal equivalent of 64.101.65.1, the IPv4 address of its interface in the IPv4 network.
When R1 receives a packet with IPv6 destination address of 2002:4065:4101:1:: (from the left IPv6 network, for example) R1 will:
* Take the IPv6 destination address of that packet (2002:4065:4101:1::) and convert it into an IPv4 address. In this case, the IPv4 address is 40.65.41.01 in hexa, which is 64.101.65.1 in decimal format.
* R1 encapsulates the IPv6 packet in an IPv4 packet with a destination address of 64.101.65.1; the packet is routed normally through the IPv4 network to R2
* R2 receives the IPv4 packet, decapsulates and routes it normally to its final IPv6 destination.

This question is in 300-101 Cisco Implementing Cisco IP Routing (ROUTE) Exam
For getting Cisco Certified Network Professional (CCNP) Routing and Switching Certificate




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