Linux Firewalls, Third Edition

Hostnames and IP Addresses

People like to use words to name things, such as giving computers names like mycomputer.mydomain.example.com. Technically, it's not the computer that's being named, but the network interface in the computer. If the computer has multiple network cards, each card will typically have a different name and address, and will most likely be on a different network in a different subdomain.

Hostname elements are separated by dots. In the case of mycomputer.mydomain.example.com, the leftmost element, mycomputer, is the hostname. The .mydomain, .example, and .com are elements of the domains this network card is a member of. Network domains are hierarchical trees. What is a domain? It's a naming convention. The hierarchical domain ...