Consider the figure given. Let A$,$ D$,$ E be hosts, B$,$ C be routers$/$switches$,$ links are: A$-$B$,$ B$-$C$,$ C$-(-$D or $-$E$)$

Problem description: Given a switched Network,

B would need the full reachability information for D and E$.$

D and E would need to know the physical addresses for all devices connected to the network beyond C$.$

Why is routing significant in this scenario as an optimal solution to the described problem?