How To Configure A DNS Server? A Comprehensive Guide

You might or might not have heard about DNS but you are using it every time you browse the internet. At its core, DNS is basically a “phonebook” of the internet. It translates domain names like “www.google.com” into IP addresses such as “142.250.80.100”. In networking, DNS is the backbone of communication that helps devices find and connect to each other. Networks (both large and small) depend on DNS to translate hostnames into IP addresses within local environments and across global systems. Without DNS, you would need to remember long strings of numbers to access websites.

In this guide, we will understand the fundamentals of DNS (its importance and how it works) and what a DNS Server is. Later, we will take a look at how to update DNS Client configuration. Last but not least, we will also see a step-by-step guide on how to configure a DNS server.

What Is DNS?

As mentioned in the introduction, the Domain Name System (DNS) is a fundamental component of the internet’s infrastructure. It operates as a hierarchical system that translates human-readable domain names into machine-readable IP addresses. For example, when you type www.example.com into a browser, DNS translates that name into its corresponding IP address, such as 192.0.2.1. This conversion allows browsers to locate the server hosting the desired website or service.

We cannot overstate the importance of proper DNS configuration. Without accurate DNS settings, you could experience disrupted access to websites. Incorrect DNS configuration can lead to downtime, which negatively impacts user experience.

Misconfigured DNS settings can expose vulnerabilities. This makes systems susceptible to attacks such as DNS spoofing or cache poisoning.

What Is DNS Server?

A DNS server, or Domain Name System server, is the actual “phonebook” component of the internet’s infrastructure.

When you try to access or request a website, your computer sends a query to a DNS server. This server then searches its database to find the corresponding IP address for the domain name. If it doesn’t have the address cached, it queries other DNS servers in a hierarchical process.

DNS servers communicate directly with DNS clients (or resolvers) that act as intermediaries. They send queries from user devices to DNS servers and rely on DNS servers to provide accurate and timely responses.

Hierarchical Structure Of DNS Servers

How does the hierarchical system of DNS simplify internet navigation? Let us find out by looking at different components of DNS.

• Root Servers: At the top of the hierarchy are the root name servers. At present, there are 13 root servers that are strategically distributed around the globe. These root servers do not contain the IP addresses for specific domain names. Instead, they direct queries to the appropriate top-level domain servers.
• Top-Level Domain (TLD) Servers: Directly beneath the root name servers are the TLD servers. These servers manage the generic top-level domains, such as “.com,” “.org,” “.net,” and country code domains (country-code TLDs or ccTLDs) like “.uk” or “.jp.” The TLD servers are responsible for maintaining records that link domain names within their respective zones to authoritative servers.
• Authoritative Servers: Next in the DNS hierarchy are the authoritative name servers. These servers hold the actual DNS records for specific domain names. They provide the final answer to a DNS query by returning the IP address of the requested domain. We can further categorize these servers into primary or master servers (that store the original zone files) and secondary or slave servers (that hold copies of zone files to provide redundancy and reliability).
• Recursive Servers Or Resolvers: Though not part of the hierarchy, recursive servers play a significant role in the DNS query process. They act as intermediaries between the end-user and the DNS servers. When a user initiates a query, the recursive resolver first checks its cache for the answer. If the answer is not cached, it starts a query process that traverses the hierarchical structure. Internet Service Providers (ISPs) and third-party DNS providers usually maintain and operate the recursive servers.

By following this hierarchical path, DNS sees to it that requests reach the right server.

How To Update DNS Client Configuration?

There are several reasons why you might want to change your DNS client configuration. For instance, using a faster DNS server can reduce load times for websites. Similarly, switching to a DNS provider that offers enhanced security features can protect against phishing attacks and other cyber threats. You might also update your DNS settings to bypass regional restrictions or access content that is otherwise unavailable in your area.

The task of updating DNS client configuration may seem technical, but it is important for maintaining a reliable and secure internet connection. Here’s a detailed step-by-step guide on how to update DNS client configurations across various operating systems.

Windows

Follow these steps to update the DNS settings on a Windows machine

• First, open the Control Panel by searching for it in the Start menu.
• Click on “Network and Internet,” then select “Network and Sharing Center.”
• Next, click on “Change adapter settings” in the left sidebar.
• Locate the network connection you are using, right-click it, and choose “Properties.”
• In the list, find “Internet Protocol Version 4 (TCP/IPv4)” and click “Properties” again.
• Select the “Use the following DNS server addresses” option.
• Enter your preferred DNS server addresses in the designated fields.
• Finally, click “OK” to save your changes and close all windows.
• Restart your computer to apply the new DNS settings.

Linux

Updating DNS settings on Linux can vary depending on the distribution you are using. For most distributions, you can configure DNS settings through the terminal.

• Open a terminal window and edit the resolv.conf file by entering sudo nano /etc/resolv.conf.
• In the file, add your preferred DNS server addresses using the format nameserver [DNS address]. For instance, nameserver 8.8.8.8 would set Google’s DNS as your server.
• Save and exit the file by pressing Ctrl+X, then Y, and finally Enter.
• To make these changes persistent across reboots, you may need to configure the DNS settings through your network manager or system configuration tool.

macOS

Here are the steps to update DNS settings on macOS.

• Start by opening “System Settings” from the Apple menu.
• Click on “Network,” and select the network interface you are currently using, such as Wi-Fi or Ethernet.
• Click on the “Details” button adjacent to the network you are connected to.
• Navigate to the “DNS” tab. Here, you can add new DNS server addresses by clicking the “+” button and entering the desired DNS addresses.
• Remove any old or unnecessary DNS addresses by selecting them and clicking the “-” button.
• Click “OK” to apply the changes, and then “Apply” to finalize the settings. The new DNS settings should now be active.

Android

Updating DNS settings on an Android device is very straightforward. These steps are specific to Samsung smartphones but they will be similar on other Android devices as well.

• First, open the “Settings” app on your device and navigate to “Connections.”
• Tap on “Wi-Fi” and click on the cog symbol (that looks like a gear) next to the network you are currently connected to.
• Expand the view by tapping on “View more” and select “IP settings.”
• Under “IP settings,” switch from “DHCP” to “Static.”
• Enter your preferred DNS server addresses in the “DNS 1” and “DNS 2” fields.
• Save your changes by tapping “Save” or “Apply.” Your device will now use the updated DNS settings.

iOS

Follow these steps to update DNS settings on an iOS device.

• Open the “Settings” app.
• Tap on “Wi-Fi” and find the network you are connected to.
• Tap the “i” icon next to the network name.
• Scroll down to the “Configure DNS” section and tap on it.
• Select “Manual” to enter custom DNS addresses.
• Tap “Add Server” to input your preferred DNS servers. You can enter multiple servers if needed.
• After entering the DNS addresses, tap “Save” to apply the changes.
• Your iOS device will now use the updated DNS settings to resolve domain names.

Popular DNS Servers

Here are some of the most popular DNS Servers and their IP Addresses:

• Google Public DNS: Primary – 8.8.8.8, Secondary – 8.8.4.4
• Cloudflare DNS: Primary – 1.1.1.1, Secondary – 1.0.0.1
• OpenDNS (Cisco): Primary – 208.67.222.222, Secondary – 208.67.220.220
• AdGuard DNS (Default): Primary – 94.140.14.14, Secondary – 94.140.15.15
• AdGuard DNS (Family Protection): Primary – 94.140.14.15, Secondary – 94.140.15.16
• Quad9: Primary – 9.9.9.9, Secondary – 149.112.112.112
• Verisign Public DNS: Primary – 64.6.64.6, Secondary – 64.6.65.6
• Comcast Xfinity DNS: Primary – 75.75.75.75, Secondary – 75.75.76.76

How To Configure A DNS Server?

Configuring a DNS server is inherently more complex than setting up a DNS client.

DNS Server Configuration For Windows Server

On a Windows Server, DNS Server software installation occurs through the Windows Server Manager.

• Open the Server Manager by clicking on the Start menu and selecting it. Once you are in the Server Manager, navigate to the “Manage” menu and select “Add Roles and Features.”
• In the “Add Roles and Features Wizard,” proceed by clicking “Next” until you reach the “Select server roles” page. Here, check the box next to “DNS Server” and click “Next.” Follow the prompts to complete the installation. The DNS Server role will now be installed on your Windows Server.
• Once installed, DNS management tools like DNS Manager simplify the configuration process. DNS Manager provides a graphical interface for creating zones, adding records, and managing other essential DNS functions.
• Open the DNS Manager by going to “Administrative Tools” and selecting “DNS.” This console provides access to manage zones, records, and server properties.
• In the DNS Manager, you need to create and configure the necessary DNS zones. Right-click on the server name in the left pane, and select “New Zone” to launch the New Zone Wizard.
• Choose the type of zone you want to create (for example, a primary DNS zone). Enter the zone name, such as your domain name (e.g., example.com), and click “Next.” Decide whether the zone should allow updates from secure dynamic updates or allow non-secure updates, then complete the wizard.
• Once you create the zone, add resource records to it. Right-click on the zone you created and select “New Host (A or AAAA).” Enter the name and IP address for the new record. For instance, you might add an A record to map www.example.com to an IP address like 192.168.1.1.
• Continue to add other necessary records, such as MX records for mail servers or CNAME records for aliases.

DNS Server Configuration For Linux Server

The process of configuring DNS on Linux servers starts with installing the necessary DNS software. For most Linux distributions, the popular choice is BIND (Berkeley Internet Name Domain).

• To install BIND, use the package manager for your distribution. On Debian-based systems, you can use the command sudo apt-get install bind9. On Red Hat-based systems, you use sudo yum install bind.
• Once the installation is complete, you have to configure the BIND service. Begin by editing the main configuration file located at /etc/bind/named.conf or /etc/named.conf, depending on your distribution. This file includes directives and options for the DNS server.
• You need to specify the directories where BIND will store zone files and logs. Update the file with the path to these directories so that the paths match your system’s directory structure.
• After configuring the main file, the next step is setting up the DNS zones. Define your zones in the configuration file by adding entries for each zone.
• For example, you will include a forward zone (that maps domain names to IP addresses) for domain name resolution and a reverse zone (that maps IP addresses to domain names) for reverse lookups. Create these zone files in the directory specified in the configuration file.
• Edit the zone files to include resource records such as A records (maps a domain name to an IP address), MX records (specifies the mail exchange servers for the domain), and CNAME records.
• Use the named-checkconf command to check the syntax of the main configuration file and named-checkzone to validate the zone files.
• Restart the BIND service using the command sudo systemctl restart bind9 (Debian) or sudo systemctl restart named (Red Hat) to apply the changes.

Testing The DNS Configuration

Once you configured the DNS server, you have to test it and check whether it resolves domain names correctly. nslookup and dig are two common tools for testing DNS resolution.

On Windows, use nslookup by entering nslookup www.example.com in the command prompt. This returns the IP address associated with the domain name. Similarly, on Linux, use dig www.example.com. dig provides more detailed information, including the time taken to resolve the query and the authority of the response.

Best Practices For DNS Server Management

In order to effectively manage a DNS server, administrators not only require technical expertise but also a commitment to provide security, reliability, and performance.

• Regular Backups Of DNS Configuration: Zone files contain critical data, including domain names and their associated IP addresses. If these files become corrupted, deleted, or compromised, it can lead to significant downtime and service disruption. Administrators have to regularly schedule backups so that they can quickly restore DNS services in the event of a failure.
• Monitoring DNS Server Performance: Slow or unresponsive servers can lead to delays in website loading, email delivery, and other internet services. To avoid these issues, administrators must continuously monitor DNS server performance using specialized tools that can track uptime, query response time, and overall server health.
• Periodic Review Of DNS Records: Over time, DNS records can become outdated or unused as domain names, IP addresses, or services change. Such old records can lead to incorrect resolutions. Administrators should periodically review DNS records (A, AAAA, MX, and CNAME) for their accuracy.
• DNS Redundancy: A single DNS server can become a point of failure. If it goes offline, users will be unable to resolve domain names. To prevent this, administrators should set up multiple DNS servers across geographically distributed locations.