单选题An IS-IS router is adjacent to and passing traffic with a neighbor. You perform a show is interface detail command and notice that for some interfaces you have a circuit type of 3. Which IS-IS level（s） is enabled on these interfaces？（）A Level 1 onlyB L
题目
单选题
An IS-IS router is adjacent to and passing traffic with a neighbor. You perform a show is interface detail command and notice that for some interfaces you have a circuit type of 3. Which IS-IS level（s） is enabled on these interfaces？（）
A
Level 1 only
B
Level 2 only
C
Level 1 and Level 2
D
Level 3 only