Linux Tactic

Demystifying DNS: The Importance of Hostname Configuration

Introduction to DNS and the History of Hostname and Domain Name

Every time you enter a website address into your web browser, you are tapping into a complex system that translates the URL into an IP address that your computer can understand. This system is known as the Domain Name System (DNS), and it has revolutionized the way we access websites on the internet.

However, this system wasn’t always in place, and the development of DNS came from a need to solve a significant problem in the early days of the internet. ARPANET and “hosts.txt” file

At the dawn of the internet, before it was even called the internet, computers needed to communicate with each other, and that communication was facilitated by the Advanced Research Projects Agency Network (ARPANET).

However, keeping track of the various computers on the network was challenging, and the process usually required people to manually update lists of computer names and their corresponding IP address values. The “hosts.txt” file was a solution to this problem.

It was a plain text file that served as a centralized directory of computer names and their corresponding IP addresses that could be accessed by other computers on the network. However, as the number of computers on the network grew, so did the number of entries in the file.

This created a logistical nightmare. The file had to be manually updated regularly, and if two computers had the same name, the system would encounter hostname conflict.

Problems with “hosts.txt” and introduction of DNS

With the growth of the internet, the “hosts.txt” file became increasingly problematic. In 1983, Paul Mockapetris proposed a solution that would eventually become the Domain Name System.

DNS was designed to make the internet more scalable while simplifying the process of resolving hostnames. The DNS system operates based on a distributed database and uses a hierarchical scheme to store information.

This system was designed to provide better scalability and faster resolution times than the “hosts.txt” file ever could. The DNS system can handle an enormous amount of users and is still in use today.

Functions of DNS

The primary function of DNS is to translate human-readable URLs into machine-readable IP addresses. When you enter a URL into your web browser, the browser sends a request to a DNS server that matches the URL with an IP address.

This process is known as resolving. The DNS system also performs several other functions such as providing information about mail servers, record keeping, and the transfer of domain names.

The system is essential to the operation of the internet, and its absence would make the internet virtually unusable.

DNS Hierarchy and Domain Name

The DNS system operates on a hierarchal model. At the top of the hierarchy is the root domain, and below it are several top-level domains.

Currently, there are over 1,200 top-level domains on the internet. The top-level domains are categorized into two groups: country-code top-level domains and generic top-level domains.

Country-code top-level domains are intended to be used for websites and services specific to a particular country or locale. Examples of country-code domains are “.us” for the United States, “.ca” for Canada, “.fr” for France, and so on.

Generic top-level domains, on the other hand, are intended to be used for a broad range of websites and services. Examples of generic top-level domains include “.com,” “.org,” “.net,” and so on.

Any website or service can use a generic top-level domain.

Subdomains and separation by period

The DNS system also permits the use of subdomains. A subdomain is any domain that is part of a larger domain.

Subdomains are separated by a period and come before the primary domain. For example, “” is a subdomain of the primary domain “”

Subdomains are used for several purposes, such as separating content types, creating different versions of a site, and making it easier to navigate to specific content.

For example, “” could be used to differentiate the shopping section of a site from the content section.


The history of DNS and the development of hostname and domain names is a testament to the ingenuity and creativity of early internet pioneers. The DNS system has made it possible to access the vast array of websites and services that make up the internet while making it scalable and faster.

DNS will undoubtedly continue to evolve and change as the internet continues to grow and develop.

Absolute and Relative Domain Names

In the domain name system (DNS), there are two types of domain names: absolute and relative. Absolute domain names include the entire domain name hierarchy from the root domain to the specific host.

Relative domain names, on the other hand, only include the parts of the domain name that are necessary to identify the host relative to the current domain name.

Bottom-to-top naming convention and interpretation

All domain names, whether absolute or relative, use a bottom-to-top naming convention. This means that the most specific part of the domain name is on the left, and the least specific part is on the right, separated by periods.

For example, in the domain name “,” “com” is the top-level domain, “google” is the second-level domain, and “mail” is the subdomain. When interpreting domain names, the DNS server reads the domain name from right to left, starting with the top-level domain and moving down the hierarchy to find the IP address associated with the host.

Rules and restrictions on domain names

There are several rules and restrictions that apply to domain names. Domain names are case insensitive, meaning upper and lower case letters are treated the same.

Domain names can only contain letters (A-Z), numbers (0-9), and hyphens (-), but not all domain name components can start or end with a hyphen. Finally, domain names have length restrictions, with the maximum length being 63 characters.

Hostname or FQDN

Fully Qualified Domain Name (FQDN) is a complete domain name that identifies a specific host within a domain. A hostname, on the other hand, is the name of a specific computer or other device connected to a network.

Hostnames can be used interchangeably with FQDNs as they are the same name; a hostname can be used on its own without the domain name.

Composition of FQDN as domain name and hostname

FQDN is composed of two parts: the domain name and the hostname. The domain name is the top-level domain and all subdomains that make up the hierarchy leading up to the host.

The hostname is the name of the specific device or host connected to the network.

Uniqueness and best practice for naming hosts

Hostnames must be unique within a network or domain, and it is best practice to name them in a descriptive and meaningful way. For example, a web server could be named “web01,” and a database server could be named “db01.” Descriptive names make it easier to identify and manage specific hosts within a network.

Possibility of multiple hostnames and resolution methods

A host can have multiple hostnames, which can be useful in situations where a host serves multiple roles or provides multiple services. When multiple hostnames are used, the DNS server will resolve all of them to the same IP address.

There are several methods for resolving the IP address associated with a hostname. One common method is the simple DNS resolution, where the DNS server looks up the IP address associated with a hostname and returns it to the client.

Clients can also cache the IP address information to speed up future requests, and DNS servers can use load balancing to distribute requests across multiple servers.


The domain name system is an essential part of the internet and enables users to access webpages and services by their human-readable names. Understanding the differences between absolute and relative domain names is crucial, and knowing how to name hosts and use FQDNs and hostnames interchangeably can improve the usability and manageability of a network.

DNS resolution methods provide for efficient identification and categorization of various services running in a network. As the internet continues to grow and evolve, so too will DNS and its technologies to ensure it remains an effective and efficient means to establish and manage internet geolocation.

Configuring Hostname

Hostname configuration is an essential part of setting up a network. Hostname configuration involves assigning a unique name to a computer or device on a network, enabling users to connect and communicate with the device using its name instead of its IP address.

Incorrect hostname configuration can cause conflicts that ultimately lead to network failures, making it crucial to understand the proper configuration process.

Specification of static hostname on Linux systems

In Linux systems, the hostname is often set during the installation process. However, it is also possible to set the hostname manually using the “hostnamectl” command.

This command allows the user to set or modify the static hostname. The syntax for setting the static hostname is as follows:


hostnamectl set-hostname hostname


The “hostname” in this command is the name given to the computer or device and should not include any spaces or special characters. View and modification of FQDN using “hostnamectl” utility

The Fully Qualified Domain Name (FQDN) is a combination of the hostname and the domain name for the computer or device.

It is important to note that changing the hostname also changes the FQDN, and vice versa. To view the current hostname and FQDN using the “hostnamectl” command, enter the following:


hostnamectl status


This will display the current hostname and FQDN for the system. To modify the FQDN using the “hostnamectl” command, use the following syntax:


hostnamectl set-hostname hostname.domain


In this command, “hostname” is the name of the computer or device, and “domain” is the domain name associated with the system. It is important to note that modifying the FQDN requires changing the hostname in the process.

Importance for network administrators to understand proper configuration

Proper hostname configuration is crucial for network administrators as it simplifies the process of managing and maintaining a network. Assigned hostnames can make management of a network easier by providing easy identification and grouping of specific devices within the network.

Hostname configuration can simplify the process of monitoring individual devices and troubleshooting network-related issues. Network administrators must ensure that they fully understand the importance of proper hostname configuration.

It is important to ensure that all hostnames are unique and relevant, making it easier to identify specific devices and monitor for potential issues. Equally important is the proper configuration of the FQDN to avoid confusion and errors that could result in system failures.


Hostname configuration is a vital aspect of setting up and maintaining a network, allowing for easy identification and management of individual devices. Administrators should prioritize the proper configuration of hostnames to ensure that all devices within the network are easily identified, monitored, and maintained properly.

Utilizing tools such as “hostnamectl” is an essential component of the hostname configuration process as it facilitates the adjustment of static hostname and FQDN. In conclusion, proper hostname configuration, when done correctly, can improve productivity and streamline network maintenance, providing a stable and reliable infrastructure.

Hostname configuration is a critical aspect of network setup and maintenance. Assigning unique and relevant hostnames simplifies network management, aids in device identification, and facilitates troubleshooting.

Through tools like “hostnamectl,” network administrators can set or modify static hostnames and view or change the Fully Qualified Domain Name (FQDN). Proper hostname configuration enhances network productivity, stability, and reliability.

It is crucial for administrators to understand the significance of proper hostname configuration to ensure efficient network operations. By following proper configuration practices, administrators can streamline network maintenance and leave a lasting impression on the overall network infrastructure.

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