Answer:
First usable address: 172.22.78.193
Last usable address: 172.22.78.206
Step-by-step explanation:
The subnet mask "/28" means that the first 28 bits of the IP address are used to represent the network address, while the remaining 4 bits are used to represent the host address.
So, the network address for the given IP address is obtained by setting all the bits in the host portion to 0, which gives us:
Network address = 172.22.78.192
Next, we can determine the valid host range by identifying the first and last usable IP addresses in the subnet. Since there are 4 bits available for the host address, there are 2^4 = 16 possible host addresses in the subnet.
However, two of these addresses are reserved for the network address and the broadcast address, leaving 14 usable addresses for hosts.
Note that the remaining two addresses, 172.22.78.192 and 172.22.78.207, are reserved for the network address and the broadcast address, respectively, and cannot be assigned to hosts.