What is FQDN | Where is FQDN Used?
FQDN stands for Fully Qualified Domain Name, which is the complete and unique name of a device or service on the internet or a local network.
Structure of FQDN
An FQDN fully specifies the hierarchical structure of a domain name and consists of the following components:
- Host name: The name of the device or service, such as “www,” “mail,” or a computer name.
- Domain name: The domain name to which the host belongs, such as “example.com.”
- Top-level domain (TLD): The top-level domain at the end, such as “.com,” “.org,” or “.net.”
Examples
- www.example.com:
- “www” → Host name
- “example” → Domain name
- “.com” → Top-level domain
This is an FQDN.
- mail.google.com:
- “mail” → Host name
- “google” → Domain name
- “.com” → Top-level domain
Where is FQDN Used?
- In DNS (Domain Name System) configurations
- Identifying servers and network devices
- Generating and verifying certificates (SSL/TLS)
- Configuring email and other network services
An FQDN starts at the top of the domain name hierarchy (the root “.” point) and specifies down to the most specific hostname. For example, “www.example.com.” is a valid FQDN, where the final dot represents the root domain. However, this trailing dot is usually omitted in common usage.