$1$ Forwarding by Routers $(20$ pts$)$

In each of the following subproblems, the ip address given is the destination ip of a packet arriving at this router. For each of them, list the links of all $($as in potentially plural$)$ the subnet masks that count as valid potential matches for the specified destinatio ip$,$ and then circle which one of those matches will be the one the packet actually gets forwarded on$.$ No explanations.

a$)171\mathrm{.}63\mathrm{.}64\mathrm{.}63$ :

b$)171\mathrm{.}64\mathrm{.}63\mathrm{.}64$ :

c$)63\mathrm{.}19\mathrm{.}5\mathrm{.}4$ :

d$)171\mathrm{.}0\mathrm{.}15\mathrm{.}171$ :