What is FQDN? Complete Guide on Fully Qualified Domain Name

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What is FQDN

What is Fully Qualified Domain Name?

A Fully Qualified Domain Name (FQDN) is the complete and address-specific domain name that is fully pointed at resources on the internet while a Partially Qualified Domain Name (PQDN) does not have the full domain hierarchy and may not be globally unique.

While FQDNs are more precise for accessing resources as they provide the exact address, PQDNS may just mention the host name without the domain or they may have an incomplete domain name.

Structure of an FQDN

An FQDN comprises two primary components: host name and domain name representing a unique role in the DNS system by referring to the place where resources could be found.

Host Name

The host name is the left part of the FQDN. It is the part of the address that is usually associated with a concrete service or resource available in the domain of the name. It is the one that is able to distinguish the resource from others and most often has its meaning coming from the characterization of its usage.

Considering this, frequently used host names are usually named as “www” for web servers, “mail” for email servers, “ftp” for file transfer protocol servers and “smtp” for Simple Mail Transfer Protocol servers. As an added element, the user may leverage custom hostnames by applicable to the organization’s specific naming rules or requirements.

Domain Name

The main component in the FQDN is the domain name, and that is the last part of the FQDN. It indicates where the resource is placed in a broader context or hierarchy. There are different levels of signs such as root names which are separated with dots, each dot represents the root level network.

The abbreviation “TLD” stands for “top-level domain,” which is the very name that is located on the rightmost label and refers to the top level of the domain hierarchy. Common TLDs include generic TLDs such as “.com” ,”.org” “.net” and country code TLDs (ccTLDs) like “.uk” “.de” and “.in“.

Additionally, the TLD can have extra sublevels after it, which can signify another subdomain, department, or location, in order to narrow the position of that resource within the network topology.

Examples of an FQDN

The FQDN function is to give a unique and precise url (uniform resource locator) for the purpose of gaining access to resources on the internet. It is essential for various networking tasks, including:

  • Website Hosting: Sites are designated with their FQDNs with a user going on to visit them through a web browser will be the pattern of use. An instance of it will be, a host name i.e. “www.example.com” for a webpage that lives on the server.
  • Email Services: The FQDN is the basis for email servers communication as it is used both for sending and receiving emails. For instance, the FQDN of an email may write as “mail.example.com“.
  • Network Communication: Within the network the devices and services refer additionally use FQDNs for ant interaction with each other over the internet.
  • System Administration: System administrators for FQDNs can configure network settings for example DNS records, routes, access control, and cyber protection.

What Is a Partially Qualified Domain Name?

A Partially Qualified Domain Name (PQDN) is a domain name that is incomplete in its hierarchy and as a result leaves a blank that was supposed to be filled.

Differently from FQDNs that provide the full and specific address for determining the location of the resources, PQDNs can include just the host name and miss the domain name or contain only an incomplete domain name.

PQDNs are a kind of locality-restricted address which can work in network environments or internal systems where the whole chain of domain hierarchy is completely unnecessary for addresses.

Like for internal corporate networks where employees typically use TLD omitted (i.e., abbreviated domain names that omit the top level domain or the other label names instead). In this context, therefore, the PQDN could be a name of the host without domain address added, for example, “server” or “printer“.

While the particulars of PQDNs can be used for relaying data within limited portions of communities or networks, the protocol is not appropriate for the internet at large. This is because PQDNs do not access in-depth context because resources in various networks and domains are not individually clearly identified by a unique identifier.

The absence of complete hierarchy in PQDNs can make them ambiguous and unclear leading the domains with similar DNS records to have conflicts in the cases where several domains with similar host names.

Partially Qualified Domain Name vs Fully Qualified Domain Name

AspectPartially Qualified Domain Name (PQDN)Fully Qualified Domain Name (FQDN)
DefinitionLacks the complete hierarchy for identifying resources.Provides a complete and specific address for locating resources.
ComponentsTypically consists of only the host name or includes an incomplete domain name.Comprises both the host name and the complete domain name.
UsageCommonly used in local network environments or internal systems where the full domain hierarchy may not be necessary.Essential for internet-wide addressing and communication, ensuring accurate and reliable access to resources.
AmbiguityMay lead to ambiguity and potential conflicts, especially in shared environments with similar host names.Ensures unambiguous identification of resources, preventing conflicts and ensuring precise routing of network traffic.
Internet CommunicationNot suitable for broader internet use due to its incomplete nature and potential ambiguity.Indispensable for internet communication, providing a globally unique and precise address for accessing resources.
Examples“server” or “printer” within a company’s internal network, where the domain hierarchy may be implicit.“www.example.com” for a website, “mail.example.com” for an email server, or “ftp.example.com” for a file transfer protocol server.
ImportanceTypically used for local addressing within specific networks or domains, offering convenience and simplicity.Critical for internet communication, ensuring seamless access to resources across different networks and domains with full context.
DNS ResolutionMay require additional configuration or context to resolve to a complete address for internet communication.Easily resolved by DNS servers to provide the complete and accurate address of the resource.
System AdministrationMay be used for internal network configurations and communication, requiring less specificity.Essential for configuring DNS records, routing, security policies, and other network settings with precision and accuracy.

When to Use an FQDN?

FQDNs are being used in different scenarios as they validate the best addressing with an exact comprehension and clarity. Here’s a detailed overview of when to use FQDNs:

Website Hosting:

These FQDNs are the locations of websites which are hosted on servers. The Internet is used only to access websites that are identified by their FQDNs. For instance, “www.example.com”, “blog.example.net” are used to identify available servers.

Therefore, as a way of providing seamless accessibility of online content, hosting providers and website administrators configure domain name system (DNS) records to associate FQDNs with the IP addresses of web servers.

Email Services:

FQDNs serve the fundamental purpose of it by serving to guide emails to the required mail servers, all in the aim of routing emails. Each email server had its FQDN, like “mail.example.com” or “smtp.example.net”. Clients and servers make a communication by using FQDNs to deliver the messages to the correct destination addresses.

Network Communication:

Within local network, but also wide area networks, the FQDNs are being used for the devices identification, such as servers, printers, routers, etc. As an example of networking devices, a network printer has the FQDN “printer.example.local,” which allows printing tasks to be carried out. FQDNs bring about frictionless interaction and secure transit of data that are tied up among networked devices.

System Administration:

It is usually FQDNs that system administrators apply to configure and manage various network settings, for example, DNS, routing tables and even firewall rules. FQDNs come handy when you’re dealing with the addresses of servers, domains, and services in configuration files and settings. Therefore, this guarantees that network configuration and administration is performed seamlessly and accurately.

DNS Resolution:

FQDNs are core elements of the Domain Name System (DNS) that on the other hand translates the human friendly domain names to IP addresses. Resolution of DNS queries by clients is accomplished by DNS servers using FQDNs among other things.

In the result, the servers provide clients with IP addresses from a structured database. The utilization of this method enables people to reach the web sources by entering the required FQDNs (Fully-Qualified Domain Names) in web browsers or email clients.

How do you look up a Fully Qualified Domain Name?

The resolution of a Fully Qualified Domain Name (FQDN) by querying the DNS system is an essential process for networks that tries to convert the FQDN into its IP address equivalent.

This process is indeed an important one as it allows us to translate human-recognizable domain names into machine-readable IP addresses, which in turn empowers devices to make communication through the internet.

To perform a DNS lookup for an FQDN, users typically have two primary methods: either installing and working on the command-line programs or using one of many online DNS lookup services available.

Command-Line Tools:

Users can carry out the DNS lookup process using the command prompt or terminal directly by utilities like nslookup (on Windows, macOS, and Linux) or dig (on Linux) for the executions of the same.

They just have to do this (type command, hit space and type FQDN ,for instance nslookup example.com then press enter), that’s it.

The command should send a query to the DNS server that is configured on the system and the server will reply with the corresponding IP addresses(es) for the specified Fully Qualified Domain Name.

Online DNS Lookup Tools:

As an alternative, users can also manage DNS queries through online lookup services that are freely accessible through various websites.

Thus, when a user visits the website, enters the address (FQDN), and hits the “Lookup” or “Search” button, then the system starts operating.

Online tool will query DNS servers with DNS requests and will display the results including resolved IP address(es) and additional DNS records and information.

As a result of the DNS resolve, the users, in their turn, can exploit the IP addresses returned and therefore get to know their location(s). This information reflects the location(s) of the server(s) associated with the FQDN.

These details are of utmost importance for network troubleshooting, verification of the correct configurations of domains, and also using their FQDNs to get resources on the internet.

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Janki Mehta

Janki Mehta is a Cyber-Security Enthusiast who constantly updates herself with new advancements in the Web/Cyber Security niche. Along with theoretical knowledge, she also implements her practical expertise in day-to-day tasks and helps others to protect themselves from threats.