A hostname refers to the name assigned to an individual machine that is a component of a computer network. Each one of these machines can be given a unique hostname (with which they can be pinpointed within the network):

  • A computer
  • A network server
  • A network printer
  • A network storage device
  • A fax machine
  • A copier
  • A modem
  • Any electronic device linked to a network

Allotting hostnames uses different naming systems. Each of these systems has a unique naming convention. The Domain Name System (DNS) is the most widespread naming system used in the Internet. DNS recognizes the host computer where the website exists. Indicated before the domain name is the host computer’s address separated by a period.

The domain name comprises a sequence of labels. Periods separate these labels. There are no spaces permitted between or within labels in the domain name. All specified labels (plus the top-level domain name or TLD) result in a Fully-Qualified Domain Name (FQDN). Strictly, FQDNS should end in a period, although these periods are usually omitted in practice. An individual label may have as many as 63 characters but the whole FQDN cannot exceed 255 characters.

Certain rules determine the validity of a hostname. A hostname should only contain characters from ‘a’ to ‘z,’ numerals from ‘0’ to ‘9,’ and the hyphen. It does not allow special characters such as the underscore (_).

For example, if is an organization’s domain name and XYZ computer is a component of that network, then the FQDN of that specific computer would be The whole FQDN would be the hostname.