Which three statements about link-state routing are true? (Choose three.)
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A. B. C. D. E. F.ADF
Answer: A, D, and F are the correct statements about link-state routing.
Explanation:
Link-state routing is a type of routing protocol that allows routers to communicate with each other by sharing information about the network topology. This information includes the network addresses of connected devices, the status of links, and the cost of using each link. Link-state protocols are used in larger networks because they are more scalable than distance-vector protocols, which rely on periodic updates.
A. OSPF is a link-state protocol:
OSPF (Open Shortest Path First) is an example of a link-state protocol. It works by flooding link-state updates (LSUs) throughout the network, so that all routers have the same information about the network topology. OSPF uses Dijkstra's algorithm to calculate the shortest path to each network destination.
D. Routes are updated when a change in topology occurs:
In link-state routing, routers only send updates when there is a change in the network topology. This means that updates are not sent as frequently as in distance-vector protocols, which send periodic updates regardless of whether there has been a change. When a change occurs, such as a link failure or the addition of a new network, OSPF routers generate new LSUs, which are flooded throughout the network.
F. Updates are sent to a multicast address by default:
Link-state routing protocols typically send updates to a multicast address instead of a broadcast address. This is because multicast addresses are more efficient, as they allow routers to receive updates only for the networks they are interested in. In OSPF, updates are sent to the multicast address 224.0.0.5 by default.
B. Updates are sent to a broadcast address:
This statement is incorrect. Link-state routing protocols do not send updates to a broadcast address. Instead, they use multicast addresses as explained above.
C. It uses split horizon:
This statement is incorrect. Split horizon is a technique used in distance-vector routing protocols to prevent routing loops by preventing a router from advertising a route back out the same interface from which it was received. Link-state routing protocols do not use split horizon because they maintain a complete map of the network topology and can calculate the shortest path to each destination.
E. RIP is a link-state protocol:
This statement is incorrect. RIP (Routing Information Protocol) is an example of a distance-vector routing protocol, not a link-state protocol. It sends periodic updates to neighboring routers, regardless of whether there has been a change in the network topology.