Fully Qualified Domain Name

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Fully Qualified Domain Name

A Fully Qualified Domain Name (FQDN) is a complete internet address, including the host name and domain name, used to uniquely identify a specific computer or resource on the internet. It specifies the full path of an individual host on a network, ensuring accurate and precise communication.

What does Fully Qualified Domain Name mean?

A Fully Qualified Domain Name (FQDN) is the complete and precise name of a domain on the internet. It consists of the Hostname and the domain name of a specific website or server.

A FQDN unambiguously identifies a domain by including all levels in the Domain Name System (DNS) hierarchy. The hierarchy starts with the root domain (represented by a dot “.”), followed by the top-level domain (TLD), then the second-level domain (SLD), and any subdomains beneath them.

For example, the FQDN for Google is “WWW.google.com”. Here, “www” is the hostname, “google” is the SLD, “com” is the TLD, and “.” is the root domain.

Applications

FQDNs are crucial in various technological applications:

  • Website Addressing: FQDNs serve as the address of websites. When you type a Web address (e.g., www.example.com) into your browser, the DNS translates the FQDN into the IP address of the corresponding server.
  • Email Routing: FQDNs are used in email addresses to identify the recipient’s domain and direct emails to the correct server.
  • Network Identifiers: FQDNs can be used to identify hosts and servers on a network. They provide precise identification, facilitating communication and resolving IP addresses.
  • Security Certificates: FQDNs are essential for issuing and verifying SSL/TLS certificates, which are used to encrypt data and secure websites.
  • DNS Records: FQDNs are used in DNS records to assign IP addresses to domain names.

History

The concept of FQDNs emerged with the development of the Domain Name System (DNS) in the early 1980s. The DNS was designed to organize and manage domain names and translate them into IP addresses.

Initially, FQDNs were only used internally within the DNS system. However, as the internet grew and the need for precise domain identification increased, FQDNs became widely adopted and standardized.

The FQDN structure and syntax were defined in Request for Comments (RFC) 1034 in 1987. Subsequent RFCs, such as RFC 1035 and RFC 2181, further refined the FQDN specifications.

Today, FQDNs are a fundamental aspect of internet infrastructure, enabling efficient and accurate communication, domain identification, and security protocols.