IS-IS Pseudonode Device

A

On broadcast networks in the IS-IS protocol, the elected DIS creates the pseudo-node, which represents itself and advertises it into the network at the appropriate level.

In IS-IS (Intermediate System to Intermediate System) network, a pseudonode represents a group of routers that share a common point of connection to another part of the network. When multiple routers are connected to a single network segment in an IS-IS network, the IS-IS protocol elects one of these routers as a designated intermediate system (DIS) to act as the representative for the group of routers on that segment.

Therefore, the correct answer to the question is A. a designated intermediate system.

Here is a brief description of each of the options:

A. A designated intermediate system (DIS): As explained above, the DIS is elected among the routers connected to the same network segment to act as the representative of the pseudonode.

B. An area border router (ABR): In IS-IS, routers are organized into areas, and ABRs connect these areas to the backbone. ABRs maintain a separate copy of the link state database for each area they connect to.

C. A router with an IS-IS export policy: An export policy in IS-IS determines which routes the router should advertise to its neighboring routers. It does not have any relation to the pseudonode.

D. A router connected to the backbone: This option is also not related to the pseudonode. All routers in the IS-IS network may be connected to the backbone at some point, but that does not make them a pseudonode.

In summary, a pseudonode in IS-IS represents a group of routers that share a common point of connection, and the designated intermediate system (DIS) represents that group.