A Fully Qualified Domain Name (FQDN) is a complete domain name that provides a detailed, clear path to a specific device or service within a network. This path is used to accurately direct traffic across a network or the “internet” rather than using the IP address the FQDN is mapped to. These requests include both web and email and, are part of DNS (Domain Name System).
A hostname is a specific name of a machine or service that forms part of the domain. An example of this would be the mail. subdomain when it is used to identify an email server or service in the FQDN mail.unlimitedwebhosting.co.uk.
The domain name component is the registered domain for example unlimitedwebhosting in www.unlimitedwebhosting.co.uk. Domain names are usually chosen to be specific and unique for the site or service they are for and a domain name that is already registered cannot duplicated under the same TLD so make sure you register your domain name today or risk missing out.
This forms the end of a FQDN and is used to potentially identify the type of organisation or its geographical region. For example in the domain unlimitedwebhosting.co.uk the .co.uk signifies this organisation is company (.co) operating in the United Kingdom (.uk).
However, the use of TLDs has evolved since their inception with many creative ways to use different TLDs including ccTLDS (Country-code top level domains) a great example of this creativity is Bitly which uses the Libyan ccTLD .ly for its domain bit.ly.
When formed these elements form the FQDN, which provides an exact address within the DNS hierarchy.
FQDNs provide the exact location within a network. This is crucial for internet services like web hosting and email hosting when misrouting can cause critical issues.
Via FQDNs DNS servers are able to map readable domain names onto IP addresses including both IPv4 and IPv6 enabling users to easily access and navigate different services across a network or internet.
Different security systems and tools rely on FQDN for configuration including SSL/TLS certificates which require that the domain and certificate name are an exact match to enable secure connections.