$ Linux Command

Network

dnsdomainname

Show the DNS domain name of the system.

dnsdomainhostnamenetwork

Additional Notes

dnsdomainname prints the DNS domain part of the system's fully qualified hostname. It extracts everything after the first dot in the FQDN as returned by hostname --fqdn.

On many systems dnsdomainname is a wrapper for hostname -d. It is useful in scripts that need the domain portion of a machine name, such as for Kerberos realm construction or DNS zone configuration. If the system does not have a domain configured, the output is empty.

Syntax

dnsdomainname

Parameters

No parameters are accepted.

Common Options

  • -d, --domain: Show the DNS domain name (same default behavior as hostname -d).
  • -F, --file file: Read the hostname from the specified file and derive the domain.
  • -h, --help: Show help text.
  • -V, --version: Show version information.

Examples

dnsdomainname

Print the DNS domain name.

hostname -d

Equivalent command. Both produce the same output.

Practical Notes

  • dnsdomainname requires the system hostname to be set as a fully qualified domain name (e.g., server.example.com).
  • The DNS domain name is often used to discover LDAP base DNs, Kerberos realms, and DNS search domains.
  • If the command returns nothing, check that /etc/hostname contains an FQDN or that hostname --fqdn produces a dotted name.
  • On most Linux systems, dnsdomainname is provided by the hostname package and is a symbolic link or alias to hostname -d.