Which Three Statements Describe The Similarities Between Ospfv2 And Ospfv3? (Choose Three.)

Which three statements describe the similarities between OSPFv2 and OSPFv3? (Choose three.)

1. Both of them are link-state protocols.
2. The source address act as the global address by them in the event of sending the OSPF messages.
3. The concept of multi areas is common in both of them.
4. Assist with the authentication of the IPsec.
5. Both of them use the alike DR/BDR election process.
6. By default, the unicast routing is enabled in them.

Answer: a correct answer is an option a (Both of them are link-state protocol.), c (the concept of multi-area is common in both of them), e (both of them use the alike DR/BDR election process).

What is OSPF?

OSPF stands for the open shortest path first protocol, the protocol is from the IP routing protocol and acts as the IGP (interior gateway protocol) for the internet which routes all the information in the IP network, related to the ip routing to the single autonomous system. 

The protocol is the link-state protocol which ensures that topology information is also exchanged with the closest network by the routers. in the AS the topology information is present in massive amounts, which allows each router to have a clear picture of the topology in the autonomous system with the help of the Dijkstra algorithm. That’s why the next-hop address is chosen by selecting the best end-to-end path of the destination in the link-state protocols.

With the help of the algorithms, the routing table is calculated by the routers. The routing table has thorough information about the destination, the protocols for the routing, the next-hop address, and the outgoing interface. Some of the features of the protocol are described in the following:

• During the fluctuation of the network topology, the protocol has to recalculate routes with the help of the Dijkstra algorithm and reduce the traffic of the routing protocol generated by it.
• The path with the same cost has the assistance of the protocols.
• From the outsider router, it can hide the topology information of the specific areas, by giving the multi-level hierarchy which is known as area routing.
• Extra routing protection and minimization in the routing protocol traffic is also a feature of this protocol.
• The authentication is enabled for all protocol exchanges so that the known protocol is present in the routing exchange of the AS.

Let’s see the difference between the OSPFv2 and OSPFv3 in the following:

Advertises: OSPFv2 advertise IPv4 routes, whereas OSPFv3 advertise routes for IPV6.

Source address: The source for the OSPFv2 is the exit interface for the IPv4 address while in the OSPFv3 the source for the message is the link-local address of the exit interface. 

DR/BDR multicast address: for the OSPFv2 the address is 224.0.0.6 while for the OSPFv3 it is FF02::6.

IP unicast routing: in IPV4 it is allowed by default, while in the IPV6 the command unicast-routing needs to be configured.

Authentication: the authentication in the OSPFv2 is either the plaintext or the MD5, whereas in the OSPFv3 it is IPV6.