CCNP: OSPF Trivia Questions For Professionals! Quiz

Explanation
LSA type 5, also known as AS External LSA, is flooded to all areas except for Stub and Totally Stubby areas. This type of LSA is used to advertise routes from one autonomous system (AS) to another. In Stub and Totally Stubby areas, only default routes are used, so there is no need to flood AS External LSAs. Therefore, LSA type 5 is the correct answer.

Explanation
ASBR stands for Autonomous System Boundary Router. It is a type of router that connects an autonomous system (AS) to an external network. ASBRs generate and advertise Type 5 Link State Advertisements (LSAs) into the OSPF routing domain. These LSAs contain information about routes to networks outside the AS, allowing OSPF routers within the AS to learn about external networks and determine the best path to reach them. Therefore, an ASBR is responsible for exchanging routing information between the OSPF domain and external networks.

Explanation
All routers in an area generate TYPE 1 Link State Advertisements (LSAs). These LSAs contain information about the router's directly connected links and are flooded within the area to ensure that all routers have the same information about the network topology. TYPE 2 LSAs are generated by the designated router (DR) on multi-access networks to advertise the network's subnet and mask. TYPE 5 LSAs are generated by autonomous system boundary routers (ASBRs) to advertise external routes into the OSPF domain. TYPE 3 LSAs are generated by area border routers (ABRs) to summarize inter-area routes.

Explanation
LSA type 7 is generated into a Not-So-Stubby-Area (NSSA) but does not leave this area. In OSPF, NSSAs are used to connect an area to an external network while still maintaining some level of control over the types of routes that are imported. LSA type 7 is used in NSSAs to advertise external routes within the area. However, unlike LSA type 5, which is used to advertise external routes throughout the OSPF domain, LSA type 7 does not leave the NSSA and is not flooded to other areas.

Explanation
The term "NET LINK STATES" refers to LSA-2 in the context of the command "show ip ospf database." LSA-2, or Link State Advertisement Type 2, represents the network link state information. It contains details about the routers connected to the network, including their IP addresses and subnet masks. By viewing the LSA-2 information, network administrators can get an overview of the network's topology and the routers involved in the OSPF routing process.

Explanation
Type 3 and 4 LSAs are only created by the ABR. This means that only the Area Border Router (ABR) is responsible for generating these LSAs. Type 3 LSAs are used to summarize inter-area routes, while Type 4 LSAs are used to advertise the existence of an Autonomous System Boundary Router (ASBR) within an area. Therefore, it is true that the ABR is the only router that creates Type 3 and 4 LSAs.

Explanation
5 and 7 are created by an ASBR.

Explanation
LSA Type 2, also known as Network LSA, is used by OSPF routers to advertise information about the routers and links within a broadcast or non-broadcast multi-access network. This LSA type includes the Router ID of the designated router (DR), which is the router responsible for maintaining the OSPF network on the multi-access network. Therefore, by examining the LSA Type 2, one can determine which router is the DR.

Explanation
Based on the information provided, the correct answer is DR (Designated Router). This can be inferred from the fact that there are 3 other routers showing as neighbors, with one of them being FULL/BDR (Backup Designated Router) and the other two being 2WAY/DROTHER (DROTHER stands for "Dynamically discovered router"). Since the question asks about the type of router that the show command was entered on, and the other routers are identified as BDR and DROTHER, the remaining option is DR.

Explanation
The fact that your router is neither the DR (Designated Router) nor the BDR (Backup Designated Router), and the two routers you are neighbors with are stuck in 2WAY/DROTHER state indicates that your router is a DROTHER (Designated Router Other). This means that your router is not responsible for sending and receiving OSPF routing updates, and it will receive less traffic compared to the DR and BDR. The routers may not have fully synchronized yet, which is why they are stuck in this state.

Explanation
DROTHERS ARE FULLY ADJACENT TO THE DR AND BDR

Explanation
The correct answer is "stub." This area type only contains O, "O IA," and "O IA*" routes.

Explanation
A totally stubby area is an OSPF area that only contains a default route and internal routes. It does not have any external routes or summary routes. In this case, the "O" stands for OSPF, and "IA" stands for Inter-Area. Therefore, the only option that can only contain "O" and "O IA" routes is the totally stubby area.

Explanation
When the command "show ip ospf border-routes" is typed on an ABR (Area Border Router), it will display the router IDs of neighboring ABRs or ASBRs (Autonomous System Border Routers), but it will not display the router ID of the local router (which is also an ABR in this case) on which the command is being executed. Therefore, the statement is true.

Explanation
In the EX start state, the routers in a network determine which router will act as the master and which will act as the slave. This determination is based on various factors such as the router's capabilities and priority. Once the master and slave routers are determined, they will perform their respective roles in the network. This process helps in establishing a hierarchical relationship between the routers and ensures efficient network operations.

Explanation
The LSACK message is used in the Link State Advertisement (LSA) flooding process to acknowledge the receipt of LSAs. However, the HELLO message does not require an LSACK to be sent because it is used for neighbor discovery and adjacency formation in OSPF. The HELLO message is sent periodically by OSPF routers to establish and maintain neighbor relationships, and LSACK is not needed for this purpose.