Hostname

In IP networks, communication endpoints are identified by IP addresses. DNS facilitates communication using hostnames by converting them into IP addresses. To handle large-scale networks like the internet, DNS introduces the concept of domains, allowing names to be managed within specific domains. When specifying communication endpoints on the internet, a combination of the domain name and hostname—known as a Fully Qualified Domain Name (FQDN)—is used.

For example, www.f5.com. is an example of an FQDN.

• In this FQDN:
  • www is the hostname.
  • f5.com. is the domain name.
  • The final dot (.) represents the root domain, signifying the entirety of the internet. This root domain is commonly omitted in practice.

Although the term FQDN can sometimes be used interchangeably with domain names, hostnames are not always mapped one-to-one with physical hosts. DNS configurations allow:

• Multiple hosts to correspond to a single FQDN (DNS round-robin).
• Multiple FQDNs to be associated with a single host (virtual host).

A growing number of websites also use hostnames identical to their domain names. For example, while www.f5.com is used as the hostname in the example above, the actual F5 website can be accessed directly via the FQDN f5.com.