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.
The remote packet delivery example is oversimplified, but you see how important IP addresses are to the packet delivery process. Let's take a minute to examine how an IP address is built. IP addresses really consist of two sections: the network section (prefix) and the host section.