A server is a computer or device on a network that manages network resources. Servers are often dedicated and they perform only their server tasks.
D (Network and subnet parts) . When using classful IP addressing concepts as described in Chapter 13, Analyzing Subnet Masks, addresses have three parts: network, subnet, and host. For addresses in a single classful network, the network parts must be identical for the numbers to be in the same network.
Note: Another way to look at this task is that you will ignore the octets indicated by the division. For instance, for 192.168.100.80/26, the result of dividing 26 by 8 is 3, so you will ignore the first three octets of the IP address, and work only with the fourth octet. This process has the same result.