Answer / Explanation:
For proper understanding, let us define what a Subnet is: Subnet which is also sometimes refereed to as a is a logical subdivision of an IP network is described as the act of segmenting a network into two or more networks is called sub-netting. Computers that belong to a subnet are addressed with an identical bit-group in their IP addresses.
In respect to the definition above, if we go ahead to calculate the new subnet masks for each sub net below, we have:
Subnet A Answer
Subnet Mask in Decimal (3 points) 255.255.255.192
Subnet Mask in Binary (2 points) 1111111.11111111.11111111.11000000
Number of Useable Hosts in this Subnet 62 available hosts
IP Network Address (2 points) 192.168.4.0
First valid IP Address (2 points) 192.168.4.1
Last valid IP Address (2 points) 192.168.4.62
Subnet Broadcast IP Address (2points) 192.168.4.63
Subnet B Answer
Subnet Mask in Decimal (3 points) 255.255.255.240
Subnet Mask in Binary (2 points) 1111111.11111111.11111111.11110000
Number of Useable Hosts in this Subnet 14
IP Network Address (2 points) 192.168.4.64
First valid IP Address (2 points) 192.168.4.65
Last valid IP Address (2 points) 192.168.4.78
Subnet Broadcast IP Address 192.168.4.79