Which of the following statements is true about the topology calculation of this network?

IS-IS is a link-state routing protocol that uses the SPF algorithm for route calculation. As shown in the figure, a campus deploys both IPv4 and IPv6, also runs IS-IS to achieve network interconnection. R2 only supports IPv4.

Which of the following statements is true about the topology calculation of this network?
A . By default, since R2 does not support IPv6, so in the shortest path tree formed by IPv6 network calculation, the path for R1 to access R4 is: R1-R3-R4
B . If you want IPv4 and IPv6 network computation to form the same shortest path tree, you need to run the ipv6 enable topology ipv6 command to enable the IPv6 capability in the IS-IS process
C . By default, in the shortest path tree formed by IPv6 network calculation, the path for R1 to access R4 is R1-R2-R4. Since R2 does not support IPv6, R2 will directly discard IPv6 packets after receiving them, causing traffic lost
D . By default, IPv4 and IPv6 networks will be calculated separately to form different shortest path trees

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Answer: C