An enterprise needs to migrate its WAN core from EIGRP to IS-IS, and in the future it wants to enable IS-IS across all other regional networks connected to the WAN core.
Which approach do you recommend this enterprise use to enable IS-IS across the WAN core?
A . Start with L1 across the WAN core and then add the regional networks as L2 each.
B . Start with L1/L2 across the WAN core and then add the regional networks as L2.
C . Start with L2 across the WAN core and then add the regional networks as L1.
D . Start with L1/L2 across the WAN core and then add the regional network as L1/L2 as well.
Answer: C