Exam JN0-649 topic 1 question 35 discussion

Correct Answer is: A and B. A needs a routing policy for L2 routes into L1 area. B is correct as External and Internal L1 routes become internal L1 routes when wide metric is used (cannot differentiate) and L1 routes are automatcally advertised to Level 2 areas.

A is right, to leak routing information from a Level 2 area to a Level 1 area, an export policy must be explicitly configured. B is right because by default, IS-IS protocol leaks routing information from a Level 1 area to a Level 2 area. C is wrong because of with "wide-metric-only", the router would advertise only extended IP reachability TLV (TLV 135) which doesn't indicate internal/external route information. All the routes would be marked as Internal and hence you will see the Level 1 external routes getting leaked into Level 2 automatically. And D may be right because Level 1 routes advertised as external routes into Level 1 are not advertised to any Level 2 routers by default, but if you configure the "wide-metrics-only" these routes become internal level 1 and will be advertised to Level 2.

Sorry, after further research, answer is A and D.

A n C correct You are correct that in ISIS (Intermediate System to Intermediate System) routing protocol, which is similar to OSPF, Level 1 (L1) and Level 2 (L2) routers do not advertise L2 routes into the L1 area by default. You are correct. In ISIS, if the "wide-metrics-only" command is configured on a router, then Level 1 (L1) routes are not advertised to Level 2 (L2) routers by default. The "wide-metrics-only" command is used to optimize the exchange of routing information between L1 and L2 areas. When this command is enabled, L1 routers only advertise summary routes to L2 routers, which reduces the amount of routing information exchanged between the two areas. However, L1 routers will not advertise individual L1 routes to L2 routers by default.

C is wrong, A is correct, but I also think B and D is correct, so the answer would be AB or AD

Support A C