Just as humans can be identifed in many ways, so too can Internet hosts. One identifier for a host is its hostname.
Hostnames are mnemonic and are therefore appreciated by humans. However, hostnames provide little, if any, information
about the location within the Internet of host.
Because hostnames can consist of variable-length aplhanumeric characters, they would be difficult to process by routers.
For these reasons, hsots are also identified by so-called IP addresses.
An IP address consists of foru bytes and has a rigid hierarchical structure. An IP address looks like 121.7.106.83,
where each period separates on ot the bytes experssed in deciaml notation from 0 to 255. An IP address is hierarchical
because as we scan the address from left to right, we obtain more and more specific information about where the host is located
in the Internet.
