Routing Protocol for First-Hand Information

A

Routing protocols are used in computer networks to allow routers to communicate with each other and exchange information about the routes to different networks. There are different types of routing protocols, including link-state, distance vector, path vector, and static protocols.

The answer to the question is A. link-state protocols use first-hand information. Link-state protocols, such as OSPF (Open Shortest Path First) and IS-IS (Intermediate System to Intermediate System), use a link-state database to keep track of the network topology. Each router in the network sends information about its directly connected links to other routers, which enables them to build a complete picture of the network topology. This information is called "first-hand information" because it comes directly from the router that is connected to the link.

In contrast, distance vector protocols, such as RIP (Routing Information Protocol), send only their routing table to their neighbors. They do not have a complete picture of the network topology, and they rely on their neighbors to provide them with information about the routes to other networks. This information is called "second-hand information" because it has been passed through one or more routers before reaching the destination router.

Path vector protocols, such as BGP (Border Gateway Protocol), also use first-hand information, but they are used mainly in large-scale service provider networks and are not commonly used in enterprise networks.

Finally, static protocols do not use any routing protocols and require manual configuration of routes. They are typically used in small networks or in situations where the network topology is very stable and changes infrequently.

In summary, link-state protocols use first-hand information to build a complete picture of the network topology, while distance vector