Exam 350-501 topic 1 question 50 discussion

D is more correct than A.

Answer D is more specific so thats the better answer indeed. Like a more specific route has priority over a less specific route ;-)

R1 is a L2 router ("area router") R2 is a L1 router ("station router") They will not form an adjacency (although if either of them were configured as L1/L2, which is the default, they could) The NET (in Cisco's format) is formed by three parts: - the area-id (single octet plus two additional bytes) - the system-id (six octets) - the SEL Systems with same area-id can become L1 neighbors. Systems with different area-ids can become L2 neighbors. The NET for R1 is: 52.0011.0000.0000.0001.00 - area-id 52.0011 - system-id 0000.0000.0001 - the SEL is 00 The NET for R2 is: 52.0022.0000.0000.0002.00 - area-id 52.0022 - system-id 0000.0000.0002 - the SEL is 00 Therefore R1 and R2 are in different areas. R2 is an L1 router, and thus cannot form an adjacency with R1 in a different area. So there are two reasons why they cannot form an adjacency. Answer: D

As someone else stated, in IS-IS there are no area "types", only levels. So D is more correct than A.

A says "configured with different area types", L1 and L2 are not area types, they are router levels.

A is not correct because even if you configure both routers to be L1 they will still not for neighborship due to different area

Sorry guys, I believe I was wrong with D: A is correct. If you change the area type on R2 to level-2 it will work D is wrong. Neighbor is not down because of the area ID, changing the area ID will not fix this if you leave the area type as level-1

D is not my favorite answer , even if you match the area, ISIS nbr wont come up as R1 is Level 1 only router and R2 is Level 2 only router, as per below documentation L1 and L2 only device will not form any ardency https://www.cisco.com/c/en/us/support/docs/ip/integrated-intermediate-system-to-intermediate-system-is-is/200293-IS-IS-Adjacency-and-Area-Types.html#anc5 (check the IS-IS Adjacency Table) so A looks a better ans if "area type" is referring to "is-tyoe"

An L1 adjacency is formed only with routers in the same area. An L2 adjacency is formed with routers in the same area or a different area. An ISIS router will form L1 and L2 adjacencies by default with a router in the same area. We see that: Router 1 is level-2 area 52.0011 Router 2 is level-1 area 52.0022

D is the correct Answer

D is correct. Read carefully https://www.cisco.com/c/en/us/support/docs/ip/integrated-intermediate-system-to-intermediate-system-is-is/200293-IS-IS-Adjacency-and-Area-Types.html

A is more correct, if we have two routers configured as L2, the area id dont matter.

For the answer A, we have 3 cases when they have same area type: 1. both are in area type 1 -> it will not work because different area (0011 vs 0022) 2. both are in area type 2 -> it will work because area difference does not matter 3. both are in area type1-2 -> it will work because area difference does not matter So the logic tells us that case 1 will invalidate this answer. The remaining vaild answer is D

D is correct. It doesn't even matter the area, as the routers will send different different hello messages (L1 and L2 hellos) and they will not form an adjacency.

D is not MORE correct than A... it's the only correct answer. It's not more specific it's not more anything... A is WRONG!!! Before you spew useless information using the Cisco documentation why don't you actually demonstrate the nonesense you are passing on.... Try in the lab and tell me I'm wrong... I dare you.

Answer is A L1/L2 L1 Adjacency if Area Id Matches, else no Adjacency L1 and L2 Adjacency if Area id Matches , else only L2 Adjacency L2 Adjacency , Area Id doesn’t matter https://www.cisco.com/c/en/us/support/docs/ip/integrated-intermediate-system-to-intermediate-system-is-is/200293-IS-IS-Adjacency-and-Area-Types.html#:~:text=Level%201%20corresponds%20OSPF%20intra,for%20easy%20configuration%20and%20deployment.

A is not correct cos even if the 2 routers are in the have the area types . D is clearly the answer here -