A network administrator wants to have the same subnet mask for three subnetworks at a small site. The site has the following networks and numbers of devices:
Subnetwork A: IP phones – 10 addresses
Subnetwork B: PCs – 8 addresses
Subnetwork C: Printers – 2 addresses
What single subnet mask would be appropriate to use for the three subnetworks?
The largest subnet in the topology has 100 hosts in it so the subnet mask must have at least 7 host bits in it (27-2=126). 255.255.255.0 has 8 hosts bits, but this does not meet the requirement of providing the maximum number of subnets.