Exam JN0-649 topic 1 question 25 discussion

Circuit type identifies the router you are running the command ON, not the connected router. In the diagram, R1 says Circuit type 2 - Therefore R1 (not R2) is level 2 only In the diagram, R2 says Circuit type 3 - Therefore R2 (and not R1) is Level 1 and level 2 Other comments here say similar but say it wrong or have the wrong answer. The circuit type in "show isis adjacency extensive" output is always related to the router you ran the command on!

Circuit type (detail output only): Displays the circuit type, which can be 1—Level 1 only, 2—Level 2 only, or 3—Level 1 and Level 2; from JNCIS-ENT study guide

labbed this and configured my MX-1 to disable level 1 and it says circuit type 2 while MX-2 says circuit 3

The circuit type in the output of show isis adjacency extensive refers to the local router's capability on that interface, not the neighbor’s. It indicates what type of IS-IS adjacency the local router is forming over that circuit (interface). However, the neighbor must support the same or a compatible circuit type for an adjacency to be established. For example: If your router is configured as L1, it can only form L1 adjacencies. If it is L2, it will only form L2 adjacencies. If it is L1/L2, it can form both types depending on the neighbor's capability.

100% B and C. I labbed this out, only takes a minute or so to spin up a simple ISIS direct topology. When modifying the Level type on an interface via the "set protocols isis interface <name> level {1 or 2} disable" command, the circuit type changes according to how the LOCAL router is configured when doing a "show isis adjacency extensive" command.

Circuit 1 - L1 Circuit 2 - L2 Circuit 3 - L1/L2

1—Level 1 only 2—Level 2 only 3—Level 1 and Level 2

@R1 Circuit Type:2, and Level: 2 (mean only in level 2) @R2 Cirtcit Type:3, and Level: 2 (mean on level 1 & level 2)

Circuit type: 1—Level 1 only 2—Level 2 only 3—Level 1 and Level 2

bc is correct takigama is right

AD Circuit type: 1 —Level 1 only. 2 —Level 2 only. 3 —Level 1 and Level 2

AD Circuit type

A and D

CC types 2 - L2 only 3- L1/L2

R1 (and not R1) has circuit type 2 which means that R2 is configured to participate in Level 2 only, answer D is correct. R2 (and not R1) has circuit type 3 which means that R1 is configured to participate in both Level 1 and Level 2, answer A is correct.

A and D is correct.

R2 has circuit type 2 which means that R2 is configured to participate in Level 2 only, answer D is correct. R1 has circuit type 3 which means that R1 is configured to participate in both Level 1 and Level 2, answer A is correct.