What Is a DNS Server? (& How Does It Work)

What Is a DNS Server? (And How Does It Work?)

A DNS (Domain name System) server is a machine responsible for resolving DNS queries, enabling your computer to locate and connect with websites and services.

In this article, we’ll explore what is a DNS server, how it works, and its significance in the functioning of the internet.

Takeaways
  • A DNS server is responsible for translating domain names into numerical IP addresses
  • There are 4 DNS servers involved in loading a web page: DNS resolver, root server, TLD server, and authoritative name server
  • DNS caching is a process of temporarily storing the IP addresses of web servers that host websites

What Is a DNS Server?

A DNS acts as an intermediary between human-friendly domain names and the numerical IP addresses that computers use to identify each other on the internet.

A DNS server is also known as a name server or domain name system server and it’s essentially a computer, equipped with a database of hostnames along with their corresponding IP addresses. Its primary function is to resolve DNS queries.

A DNS query, also known as a DNS request, is a request for information about a certain domain name sent from the user’s computer to a DNS server. By resolving a DNS query, the domain name system can translate human-readable domain names into IP addresses that computers understand.

What Are DNS Root Servers?

Final: What Is a DNS Server? (And How Does It Work?)

Image Source: root-servers.org (Screenshot)

DNS root servers serve as the starting point for DNS queries, playing a pivotal role in the process of translating human-readable domain names into IP addresses.

There are 13 sets of root server clusters distributed globally, each managed by different organizations.

The primary function of DNS root servers is to respond to DNS queries by directing them to the appropriate top-level domain (TLD) name servers, which then guide the query further down the DNS hierarchy to the authoritative name servers responsible for the specific domain being sought.

While root servers do not store information about individual domain names, they serve as the foundation upon which the hierarchical DNS structure is built, ensuring the internet’s coherent and efficient operation by assisting in the resolution of domain names to their respective IP addresses.

DNS Server Example

Suppose you want to visit the website www.example.com using your web browser. When you enter this domain name into the browser’s address bar and press Enter, your computer sends a DNS query to a DNS server.

The DNS server then looks up its database to find the corresponding IP address for www.example.com. Let’s say it finds that the IP address associated with www.example.com is 203.0.113.1.

The DNS server sends this IP address back to your computer, which then uses it to establish a connection to the web server hosting www.example.com. Your web browser can now load the website’s content because it knows the machine-readable IP address to reach the server where the website is hosted.

In this way, DNS servers play a critical role in translating user-friendly domain names like www.example.com into the actual IP addresses necessary for computers to communicate over the internet.

How DNS Servers Work

Below, we’ll detail how DNS servers work when translating domain names into IP addresses and resolving DNS queries.

What a DNS Server Does

DNS servers resolve DNS queries. When a user or a device requests access to a website or service by entering a domain name, and once the server resolves a DNS query, the DNS transforms this human-readable domain name into a machine-readable IP (Internet Protocol) address.

This process enables devices on the internet to locate and connect with the requested internet resource. DNS servers act as intermediaries, resolving the DNS query by providing the necessary IP address information, and enabling seamless communication on the internet.

4 DNS Servers Involved in Loading a Webpage

Loading a webpage involves interactions with four different types of DNS servers: DNS Resolver, Root Server, TLD (Top-Level Domain) Server, and Authoritative Name Server. Here’s an overview of their roles, key differences, and how they work together.

DNS Resolver

The DNS resolver, often in your device or your ISP’s network, initiates DNS queries and manages DNS resolution on behalf of users or devices.. It begins by checking its cache for the IP address of the requested domain. If not found, it contacts a DNS root server to start the resolution process.

Root Server

The root servers are globally distributed clusters (13 in total) serving as the entry point in DNS resolution. Their main role is to provide referrals to the relevant TLD servers based on the TLD of the queried domain. They don’t store specific IP addresses but guide the resolver to the next step.

TLD Server

Top-level domain servers are responsible for managing TLDs like “.com” or “.org.” They maintain information about domain names within their TLD and delegate queries to authoritative name servers for second-level domains. When contacted by the resolver, a TLD server responds with the IP address of the authoritative name server for the second-level domain.

Authoritative Name Server

Authoritative name servers hold IP address information for specific domains. When the resolver receives the IP address of the authoritative name server for the second-level domain, it queries this authoritative server directly. The authoritative name server responds with the precise IP address for the requested domain, enabling the resolver to establish a connection with the corresponding web server, thus loading the webpage or internet resource.

3 Types of DNS Queries

Three types of DNS queries play important roles in the DNS resolution process.

  • Recursive DNS Query: In a recursive query, the DNS resolver asks a DNS server to fully resolve the queried domain name. The DNS server receiving the query is responsible for following the entire resolution process. Usually, end-user devices use recursive queries to quickly obtain IP addresses.
  • Iterative DNS Query: The DNS resolver requests DNS information from a DNS server but doesn’t expect the server to fully resolve the query. The server receiving an iterative query provides the best information it has available, which may include referrals to other DNS servers. DNS servers communicating with each other to collaboratively resolve DNS queries typically use iterative DNS queries.
  • Non-Recursive DNS Query: This query is a request made by one DNS server to another DNS server where the second server is expected to provide a specific answer without referring to the querying server elsewhere. This type of query is used when DNS servers need to exchange information about specific domain names without delegating further resolution as well as to cache DNS information efficiently.

What Is DNS Caching?

DNS caching is a process used by the DNS to store the locations (IP addresses) of web servers that host websites.

This process is essential to speeding up internet browsing and reducing the load on DNS servers, which are responsible for translating human-friendly domain names (like www.example.com) into machine-readable IP addresses (such as 192.0.2.1).

When a user attempts to visit a website, their computer will first check if the IP address for that site’s domain name is stored in its local DNS cache, which is a temporary database maintained by the operating system.

If the information is present in the cache, the web browser can bypass the need to request a remote DNS server, allowing the webpage to load more quickly. This local caching also occurs at different nodes across the internet, including your router and your Internet Service Provider (ISP), further reducing the need for repetitive DNS lookups for popular websites.

However, DNS caches have a specified ‘time to live’ (TTL) period after which the stored information is considered outdated and is purged from the cache.

This mechanism ensures that changes to DNS records, like a change in the IP address of a website, get propagated throughout the internet in a controlled fashion. The TTL is set by the administrators of the DNS records and can vary greatly depending on the needs of the particular domain.

When the cache expires or if the domain is not present in the cache, the DNS resolver will query an upstream DNS server to obtain the necessary IP address, update its cache with this new information, and proceed to direct the user’s browser to the requested website.

Where Does DNS Caching Occur?

DNS caching occurs at various levels within the network stack, and two notable types are browser DNS caching and operating system (OS) level DNS caching.

Browser DNS Caching

  • Web browsers (e.g., Chrome, Firefox, Safari) maintain their DNS caches
  • Stores domain names and corresponding IP addresses locally when visiting a website
  • Browser cache is the first check for a URL, allowing immediate resolution if data is found
  • Separate caches for each browser, with varying retention times based on browser settings
  • Browser caches are smaller with a shorter TTL, often cleared with regular closures and restarts

Operating System (OS) Level DNS Caching

  • The computer or device’s OS maintains a DNS cache for all network communication software
  • Serves as an intermediary between browser and more distant DNS caches (e.g., ISP level)
  • Checked before external DNS server requests; if information is absent, it queries and caches the response
  • OS cache has a longer TTL than browser caches and is managed automatically by the system
  • Significant in reducing DNS traffic and enhancing access times for frequently visited websites

Primary and Secondary DNS Servers

Primary and Secondary DNS servers work together to ensure a reliable and continuous Internet browsing experience. The primary DNS server is the first point of contact for DNS queries; it holds the DNS records and manages the DNS zone files which contain the mappings of domain names to IP addresses.

If the primary DNS server cannot be reached due to maintenance, network issues, or unexpected downtime, the secondary DNS server comes into play.

It acts as a backup, holding a copy of the zone files from the primary server. This redundancy is crucial for fault tolerance and load balancing. When the primary server is back online, any changes to the DNS records are replicated to the secondary to ensure both servers hold the same, up-to-date information.

How to Find Out What Your DNS Server Is with DNS Lookup

The process to find what your DNS Server is with DNS lookup depends on which system you use. We outlined the process for both Windows and MacOS users.

How to Find Your DNS Server on Windows:

  1. Navigate to the Command prompt by clicking on Start Menu and typing cmd. Press enter.
  2. Enter nslookup google.com and press Enter.
  3. You’ll get values that will show the server, name, and other parameters. Search for “Addresses” which will show your DNS server address.

Final: What Is a DNS Server? (And How Does It Work?)

How to Find Your DNS Server on MacOS:

  1. Press the Command Key + Space Bar to open the Terminal
  2. Type nslookup google.com and hit Enter.
  3. Search for the “Addresses” line to reveal your DNS server address.

How to Change Your DNS Server

You might want to change your DNS server settings for several reasons:

  • Improved Speed: Some DNS servers can respond to queries faster than others, which can reduce the time it takes to load a webpage.
  • Reliability: If a user often experiences downtime with their current DNS server, they might switch to a more reliable one.
  • Security: Certain DNS services offer additional security features that help block malicious websites and filter out harmful content.
  • Privacy: Some users prefer DNS servers that do not log queries or that minimize the amount of data they collect.
  • Parental Controls: Some DNS providers offer parental control features that restrict access to adult content.
  • Bypassing Restrictions: In some cases, changing the DNS server can help bypass internet censorship or access geo-restricted content.

Here’s how to change the DNS server on Windows:

  1. Navigate to the Start Menu. Go to Settings
  2. Select Network & Internet

Final: What Is a DNS Server? (And How Does It Work?)

  1. Navigate to Advanced Network Settings and then click Change Adapter Options.

Final: What Is a DNS Server? (And How Does It Work?)

  1. Right-click on the network connection that you want to edit. For example, if you’re connected to a Wi-Fi network, right-click on your wireless network. If you use an Ethernet cable to connect to your network, right-click that.
  2. Select Properties. Select Internet Protocol Version 4 (TCP/IPv4) You might need to scroll down to find it.
  3. Click Properties and then click Radius next to Use the following DNS server addresses.
  4. Enter a new DNS address.
  5. Click OK.

Here’s how to change the DNS server on MacOS:

  1. Press the Apple icon located in the top-left corner of your screen. Click System Preferences.
  2. Click Network
  3. Select the network connection on which you want to change the DNS server. There will be different network connections on your left sidebar.
  4. The connections that have a green circle next to them are your active connections, which means you’re currently using them. The connections that you don’t use will have a red circle to them.
  5. Once you selected the connection, click Advanced option in the bottom-right corner of the window.
  6. Navigate to the DNS tab on top of the window
  7. Click the plus (+) icon located at the bottom of the DNS Servers tab.
  8. Enter new DNS addresses for the primary DNS address and secondary DNS address.
  9. Click OK to apply changes and return to the Network window
  10. Finally, press Apply to finalize all the changes.

Common DNS Server Problems

DNS servers are crucial in the functioning of the internet, but they can encounter various problems that disrupt normal service. Here are some common issues.

Malware Attacks that Change DNS Server Settings

Malware can target DNS servers or the DNS settings on a user’s device. These attacks usually involve DNS hijacking or poisoning:

  • DNS Hijacking: Malware changes the DNS server settings on the victim’s device to redirect them to fraudulent websites or to intercept internet traffic.
  • DNS Poisoning: Malware introduces corrupted DNS data into the cache of a DNS server, leading users to incorrect and potentially malicious websites.

Both methods can be used to steal sensitive information, serve malware, or manipulate web traffic.

How to Protect Yourself from DNS Attacks

To guard against DNS attacks, consider the following steps:

  • Keep Software Updated: Regularly update your operating system and antivirus software to protect against the latest threats.
  • Use Reputable DNS Services: Consider using DNS services with built-in security features, such as DNSSEC (DNS Security Extensions).
  • Secure Network Devices: Change default passwords on routers and network devices and keep their firmware updated.
  • Employ Network Firewalls: Use firewalls to block malicious traffic and potentially dangerous requests.
  • Enable DNSSEC: This adds a layer of authentication to DNS responses, helping to prevent spoofing.
  • Regularly Monitor Networks: Watch for unusual traffic patterns or altered DNS settings.

DNS Server Not Responding

When a DNS server isn’t responding, it may be due to incorrect DNS settings, network connectivity issues, or problems with the DNS service itself.

How to Fix This DNS Server Problem

  • Restart Your Router: Sometimes, the issue can be resolved by simply restarting your router or modem.
  • Check Your Internet Connection: Verify that your internet connection is working correctly by trying to connect to a website using its IP address instead of its domain name.
  • Change DNS Servers: You can switch to public DNS servers such as Google DNS (8.8.8.8 and 8.8.4.4) or Cloudflare DNS (1.1.1.1).
  • Flush DNS Cache: Clearing your DNS cache can resolve the issue if the cache is corrupted. On Windows, you can do this by running the command ipconfig /flushdns in the Command Prompt.
  • Check Firewall and Antivirus Settings: Ensure that your firewall and antivirus programs are not blocking your DNS server.
  • Update Network Adapter Drivers: Outdated network drivers can cause issues with DNS. Make sure your network adapter drivers are up to date.
  • Disable Secondary Connections: Disable any unused network connections in your network settings to avoid conflicts.
  • Restart Your Computer: As with many technical issues, sometimes a simple system restart can resolve the problem.

DNS Server Unavailable

When you encounter this error, it generally means that your device can’t resolve domain names into IP addresses, which is necessary to load websites and access online services. This could happen for several reasons:

  • Connectivity Issues: Your device might not be connected to the internet, or there could be a problem with your router, modem, or network configuration that’s preventing access to the DNS server.
  • Server Downtime: The DNS server itself could be experiencing downtime due to maintenance, technical issues, or a DDoS attack.
  • Misconfiguration: The DNS settings on your device or within your network might be configured incorrectly, pointing to a server that doesn’t exist or isn’t operational.
  • Firewall or Security Software: Sometimes, firewall settings or security software can block access to certain DNS servers.
  • ISP Problems: Occasionally, the issue could be with your Internet Service Provider if their DNS servers are down or experiencing issues.

How to Fix This DNS Server Problem

  • Check the DNS Service Status: See if the DNS service is down for everyone or just for you using online tools.
  • Use Alternative DNS: Temporarily switch to a public DNS server to see if the problem is with the default server provided by your ISP.
  • Restart Your Devices: Sometimes, simply restarting your computer and networking equipment can resolve the issue.
  • Check for Incorrect Settings: Make sure your own DNS server settings haven’t been improperly altered.

Final Word

A DNS server is an essential network component that enables computers to access different websites, as well as other resources.

But, to have a DNS server locate your website, you first need one. Check out our best website builder tools, and while you’re there, select the best web hosting service for your needs.

Next Steps: What Now?

Learn More About DNS

Frequently Asked Questions

What is a DNS server for dummies?

A DNS server is like an address book for the internet. When you want to visit a website, you type in a web address (like www.example.com), but computers don’t understand words – they need numbers (IP addresses) to find websites.

The DNS server takes the web address you type in and looks up the corresponding number (IP address) so your computer can visit the website. It’s like looking up someone’s name in a phone book to get their phone number.

What is a DNS server on Android?

On an Android device, a DNS server functions just as it does on any other device. It translates domain names (like www.example.com) into IP addresses that your device uses to access internet resources.

Android devices automatically use the DNS server provided by the Wi-Fi or mobile data network you’re connected to, but you can also set a custom DNS server in the Wi-Fi settings or use third-party apps for more DNS options.

What is a DNS server IP address?

A DNS server IP address is the numerical label assigned to a DNS server on the internet. This address is used by your computer or device to communicate with the DNS server when it’s trying to translate a domain name into an IP address. For example, one of Google’s DNS server IP addresses is 8.8.8.8, which you can set your device to use for translating domain names.

What is a DNS server for wifi?

A DNS server for Wi-Fi is the DNS server that your wireless device uses when it’s connected to a Wi-Fi network. Typically, when you connect to a Wi-Fi network, the router automatically assigns a DNS server to your device, often the ISP’s own DNS server. However, you can change this in your Wi-Fi network settings to use a different DNS server, like Google DNS or OpenDNS, if you prefer.

Sonja Vitas
Edited By:
Sonja Vitas
Content Editor

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