A fully qualified domain name (FQDN), sometimes also referred to as an absolute domain name,Cite error: A <ref>
tag is missing the closing </ref>
(see the
help page).
The topmost layer of every domain name is the
DNS root zone, which is expressed as an empty label and can be represented in an FQDN with a trailing dot, such as somehost.example.com.
. A trailing dot is generally implied and often omitted by most applications. Trailing dots are required by the standard format for DNS
zone files, as well as to disambiguate cases where an FQDN does not contain any other label separators, such as the FQDNs for the root zone itself and any
top-level domain.
[1]
The length of each label must be between 1 and 63 octets, and the full domain name is limited to 255 octets, full stops included. [2]
A relative domain name is a domain name which does not include all labels. [3] It may also be referred to as a partially-qualified domain name, or PQDN. [4] Hostnames can be used as relative domain names.
Dot-separated fully qualified domain names are the primarily used form for human-readable representations of a domain name. Dot-separated domain names are not used in the internal representation of labels in a DNS message [5] but are used to reference domains in some TXT records and can appear in resolver configurations, system hosts files, and URLs.
Web addresses typically use FQDNs to represent the host, as it ensures the address will be interpreted identically on any network. Relative hostnames are allowed by some protocols, including HTTP, but disallowed by others, such as the Simple Mail Transfer Protocol (SMTP). [6]
A fully qualified domain name (FQDN), sometimes also referred to as an absolute domain name,Cite error: A <ref>
tag is missing the closing </ref>
(see the
help page).
The topmost layer of every domain name is the
DNS root zone, which is expressed as an empty label and can be represented in an FQDN with a trailing dot, such as somehost.example.com.
. A trailing dot is generally implied and often omitted by most applications. Trailing dots are required by the standard format for DNS
zone files, as well as to disambiguate cases where an FQDN does not contain any other label separators, such as the FQDNs for the root zone itself and any
top-level domain.
[1]
The length of each label must be between 1 and 63 octets, and the full domain name is limited to 255 octets, full stops included. [2]
A relative domain name is a domain name which does not include all labels. [3] It may also be referred to as a partially-qualified domain name, or PQDN. [4] Hostnames can be used as relative domain names.
Dot-separated fully qualified domain names are the primarily used form for human-readable representations of a domain name. Dot-separated domain names are not used in the internal representation of labels in a DNS message [5] but are used to reference domains in some TXT records and can appear in resolver configurations, system hosts files, and URLs.
Web addresses typically use FQDNs to represent the host, as it ensures the address will be interpreted identically on any network. Relative hostnames are allowed by some protocols, including HTTP, but disallowed by others, such as the Simple Mail Transfer Protocol (SMTP). [6]