Using the network Figure $3$ below, answer the following:

A$.$ Explain the term $"$AD$"$ shown in the network below.

B$.$ In routing protocols.

a$.$ If a host from Network $1$ would like to communicate with Network $2,$ and

suddenly Network $2$ was down, explain and demonstrate a Network Looping can

occur between routers $($A and B$).$

b$.$ Explain a solution that can be applied to prevent Network Looping.

C$.$ Explain the RIP routing protocol, and show how packets can be directed from PC$0$ to PC$5$ based on the routing tables in each router.

D$.$ What is the Bellman$-$Ford algorithm? Explain in what cases can be helpful.

E$.$ Using the shortest path first, find the shortest path to all routers from router A based on Dijkstra's algorithm. And also show the shortest path from A to E$.$