OSPF Review (The Second Best IGP)

All routers in a non-Area 0 area of OSPF share the same database of all links in the area and compute the Dijkstra algorithm on that same dataset. This ensures a loop-free environment by allowing each router to have a complete and consistent view of the network topology. The "Link State Database" (LSDB) is crucial in OSPF, as it stores all the link state advertisements (LSAs) and ensures synchronization among routers. OSPF messages contain mechanisms to update missing LSAs and maintain LSDB synchronization, further enhancing the loop-free topology.

Poison reverse was a hack!
Split horizon as a concept sort of lives on with many protocols. Don't advertise out interfaces from where you learned the information. That just sounds like good life advice doesn't it?

OSPFv2 is used when working with IPv4 networks, as it is specifically designed for this protocol. On the other hand, OSPFv3 is used for IPv6 networks, providing support for the newer version of the Internet Protocol. The statement "All of the Above" is not a valid explanation as it does not provide any specific information about when to use OSPFv2 versus OSPFv3.

the Bigger acronym has the bigger word (in this case):
ASBR = Boundary
ABR = Border

Split Horizon is not "supported" in OSPF. I wonder WHY? Hmmm good question.

The explanation for the given correct answer is that OSPF (Open Shortest Path First) uses Protocol 89 for transport, while EIGRP (Enhanced Interior Gateway Routing Protocol) uses Protocol 88 for transport. This means that OSPF and EIGRP use different protocols for communication and data exchange. Therefore, the statement "OSPF use Protocol 89 for transport and EIGRP uses Protocol 88 for Transport" is true.

Intra-Area routes are preferred over Inter-Area routes because they have a lower cost and are more efficient. Intra-Area routes are within a single area of a network, allowing for faster communication and less congestion. Inter-Area routes, on the other hand, involve communication between different areas, which can lead to higher costs and slower transmission speeds. Therefore, it is true that Intra-Area routes are preferred over Inter-Area routes.

ASBR (Autonomous System Boundary Router) is responsible for exchanging routing information between different autonomous systems. Type 3 LSAs (Link State Advertisements) are used to advertise inter-area routes. ASBRs send Type 5 LSAs into Area 0, not Type 3 LSAs. Therefore, the given statement is false.

For OSPFv2, 224.0.0.5 is indeed used when sending to all OSPF routers, and 224.0.0.6 is used for routers sending updates to the DR and BDR. However, it's essential to note that this applies specifically to OSPFv2, not OSPFv3, which is designed for IPv6.

The given explanation suggests that the answer is "Yes" because historically, E2 routes were used when the cost to reach the ASBR was insignificant compared to the low bandwidth of the external link. Additionally, E2 routes were computationally easier to handle since the cost was the same from all OSPF routers and no calculations were needed.

ALL ROUTERS: this is a trick question. I was asked this on an exam before. The answer is if the OSPF AREA has multiple Areas the LSDB will not be the same on ALL ROUTERS.