A router has just received the following new IP addresses: 173.82.160.0/21, 173.82.168.0/21, 173.82.176.0/21, 173.82.184.0/21, and it has to update its routing table. The first two addresses use outgoing link number 7, and the last two addresses use outgoing link number 5.

a. Can they be aggregated in such a way that exactly one entry is added to the forwarding table? If they can, how? If they cannot, why not?

b. Can they be aggregated in such a way that exactly two entry is added to the forwarding table? If they can, how? If they cannot, why not?

c. Can they be aggregated in such a way that exactly three entry is added to the forwarding table? If they can, how? If they cannot, why not?