A Fully Qualified Domain Name (FQDN) is a complete domain name that specifies the exact location of a website or other network resource on the internet. It consists of a series of labels, separated by periods, that identify the specific domain and subdomains associated with the website.
The first label in an FQDN is the hostname, which identifies the specific device or server that hosts the website or network resource. The hostname is followed by the top-level domain (TLD), which is the highest level of the domain name hierarchy and identifies the type of organization or purpose of the website. Some common TLDs include .com, .org, and .net.
The FQDN also includes any subdomains that are associated with the website. A subdomain is a domain that is part of a larger domain and is typically used to organize different sections or functions of a website. For example, the subdomain "mail" in the FQDN "mail.example.com" could be used to host an email service for the website "example.com."
FQDNs are used to uniquely identify and locate websites and other network resources on the internet. When you enter an FQDN into a web browser, the browser uses the Domain Name System (DNS) to resolve the FQDN into the corresponding IP address, which is the numerical label assigned to each device connected to the internet. The IP address is then used to connect to the correct server and access the desired website or network resource.
FQDNs are also used in other applications and protocols that require the identification and location of network resources, such as email servers, file servers, and databases. In these cases, the FQDN is used to specify the location of the resource and establish a connection to it.
In summary, a Fully Qualified Domain Name is a complete and unique address that identifies a specific website or network resource on the internet, and it is used to locate and access that resource through the DNS and other protocols.