Explanation: Classful routing means that all hosts in the internetwork use the same mask. Classless routing means that you can use Variable Length Subnet Masks (VLSMs) and can also support discontinuous networking.

Explanation: When a network goes down, the distance-vector routing protocol initiates route poisoning by advertising the network with a metric of 16, or unreachable.

Explanation: RIPv2 is pretty much just like RIPv1. It has the same administrative distance and timers and is configured just like RIPv1.

Explanation: Multiple routing protocols are required only when we need to migrate from one routing protocol to another, or when we are using routers from multiple vendors, or when there are host-based routers from multiple vendors. Routing is not a layer-2 function so we don’t require multiple routing protocols when new layer-2 switch is added.

Explanation: OSPF stands for Open Shortest Path First. It is a Link state routing protocol. IP EIGRP and RIPv2 can be redistributed into OSPF by a Cisco router.

Explanation: Routing feedback is an anomaly in which the routing protocols go back and forth between one route and another. Routing feedback is a reason for avoiding doing route redistribution on two routers between the same two routing domains.

Explanation: Sources of routing information is the administrative distance rank. It is used by routers to select the best path when there are different routes to the same destination. It’s used only two different routing protocols are being used.

Explanation: Neighbor adjacency refers to the formal handshake performed by neighboring routers. It is to be done before the router share any routing information. RIP V2 maintains neighbor adjacencies.

Explanation: The diffusing update algorithm (DUAL) is used to maintain backup routes to a destination for when the primary route fails. EIGRP routing protocol implements the diffusing update algorithm.