There are two primary addresses assigned to a host device:

Both the MAC address and IP address work together to identify a device on the network. The process of using the MAC address and the IP address to find a computer is similar to the process of using a name and address of an individual to send a letter.

A person's name usually does not change. A person's address on the other hand, relates to where they live and can change.

Similar to the name of a person, the MAC address on a host does not change; it is physically assigned to the host NIC and is known as the physical address. The physical address remains the same regardless of where the host is placed.

The IP address is similar to the address of a person. This address is based on where the host is actually located. Using this address, it is possible for a frame to determine the location of where a frame should be sent. The IP address, or network address, is known as a logical address because it is assigned logically. It is assigned to each host by a network administrator based on the local network that the host is connected to. The figure demonstrates the hierarchical nature of locating an individual based on a “logical” address. Click each grouping to view how the address filters down.

Both the physical MAC and logical IP addresses are required for a computer to communicate on a hierarchical network, just like both the name and address of a person are required to send a letter.