What is a Fully Qualified Domain Name (FQDN)?
An FQDN is a domain name that completely and uniquely identifies one and only one host on the Internet. It has this general syntax:
This is the minimal syntax for an FQDN. It is possible to have even more complete domain names that are still FQDN. An example would be a domain name of this general syntax:
An FQDN can be broken down into four parts:
- Hostname: www, mail, ftp, store, support, etc.
- Domain: apple, microsoft, ibm, facebook, etc.
- Top level domain (TLD): .com, .net, .org, .co.uk, etc.
- Trailing period: the final period in an FQDN indicates the end of the name, implying the previous string is the TLD.