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Fully Qualified Domain Name (FQDN)


Internet standard. A human-readable label that identifies a specific server on the internet.

A Fully Qualified Domain Name (FQDN) sets the complete address for a specific location in the Domain Name System (DNS) hierarchy. This is also known as the absolute domain name.

An FQDN consists of four parts. Using the example of mail.sys.example.com, these parts include:

PartAbbrDescriptionExample
Top level domainTLDTrunk of the DNS hierarchy.com
DomainBranding for a specific entity on the internet.example
Partially qualified domain namePQDNVirtual space that identifies part of an entity, like its systems team.sys
HostnameLabel for a specific server or host in the domainmail

To connect to a server or service on the internet, always use the FQDN.