Based on the information in this graph, which of the following is the likely cause?

The IS-IS Level-1 neighbor relationship between R3 and R4 is not established.

[R3] display isis error

Hell packet errors ：

… …

Repeated System ID ： 0 Bad Circuit Type ： 0

Bad TLV Length ： 0 Zer Holding Time ： 0

Unusable IP Addr ： 0 Repeated IPV4 Addr ： 0

Mismatched Area Addr （ L1 ）： 13 Mismatched Prot ： 0

SNPA Conflicted （ LAN ）： 0 Mismatched Level ： 0

Mismatched Max Area Addr ： 0 Bad Authentication ： 0

… …

[R3]

Based on the information in this graph, which of the following is the likely cause?
A . The IIH authentication of R3 and R1 failed
B . The circuit-type of the interconnection interface of R3 and R4 does not match
C . The IS-Level of R3 and R4 do not match
D . The area numbers of R3 and R4 are different

View Answer

Answer: D