What Is a DNS Server, and How Does It Work?

What Is a DNS Server, and How Does It Work?

Key Points:
  • DNS Servers are dedicated computers that look up the IP addresses associated with domain names. The DNS server stores a catalog of all the public IP addresses as well as domain names in use today.
  • You can now find new uses for DNS mainly due to NS1 and other next-generation DNS services enabling advanced traffic routing capabilities.
  • As part of DNS assault like cache poisoning, malefactors introduce false data into the DNS, usually by altering the cache.

You might already know that when you open up a web browser and type in a URL, your browser is requesting data from a web host server. However, the Domain Name System (DNS) also plays a part in the communication between your browser and the server. Protecting your privacy and speeding up your web browsing are just two of the many benefits of a Domain Name System (DNS).

DNS: Overview

In other words, DNS Servers are dedicated computers that look up the IP addresses associated with domain names like “example.com.” The DNS server stores a catalog of all the public IP addresses as well as domain names in use today.

An Internet Protocol (IP) address, in either the IPv4 or IPv6 format, is a unique identifier for each device on the internet. The same is true of servers that host websites on the Internet.

There are situations when many IP addresses can belong to a single domain name. For instance, huge websites such as Google have users from all over the world searching their servers.

Even if both the browser’s address bar and the server’s address bar have the same domain name, the server that a computer in Australia queries may not be the same as the server that a computer in Singapore actually reaches out to. When this occurs, DNS caching becomes useful.

Where Does DNS Come into Play?

When you go online and type a domain name into a browser, your computer takes the lead and resolves the hostname for you. Then, your machine consults its local DNS cache for the IP address corresponding to the domain name.

By the way, your computer keeps recently-saved data in this cache, so a webpage will load faster if it can be accessed from the local machine. If your machine does not already know the answer, it will issue a DNS query to find it.

It suggests that DNS be used for:

  • Connecting databases, app servers, and middleware in applications,
  • Resolving hostnames,
  • Establishing virtual private networks,
  • Routing messages to webmail services and email servers,
  • Initiating peer-to-peer sharing programs,
  • Communicating between gateways, IoT devices, and servers.

These are only some of the ways you can see DNS in action, but it has evolved considerably in the last two decades or so. You can now find new uses for DNS mainly due to NS1 and other next-generation DNS services enabling advanced traffic routing capabilities.

Some of these next-generation services include:

  • Global Server Load Balancing – this enables fast routing of connections between data centers worldwide.
  • Multi CDN – this involves sending users to the CDN for the best online experience.
  • Geographical Routing – this involves the identification of a user’s physical location and then routing them to the nearest resource.
  • Data Center and Cloud Migration – this helps manage traffic from on-premise resources to different cloud resources.

How Does a DNS Server Work?

The DNS helps identify computers reachable through the Internet.


A DNS server comes into action the moment you enter a domain name into your browser. Here are the steps involved in how it works.

1. Requesting Website Info

When you enter the domain name, the computer automatically resolves the hostname and looks for the IP address associated with it. Initially, it looks for it in its local DNS cache, but if it is unavailable locally, it initiates a DNS query to get that info.

2. Connecting with the Recursive DNS Server

A recursive name server is one that processes queries for the sake of providing further information. In contrast to traditional DNS servers, they do not maintain any records on their own.

The IP address is associated with an entry in the cache memory, accessed when a query is received. The query sender gets a response in case the recursive name server has any info.

 The query automatically transfers to another recursive name server if it lacks the record. This keeps happening until the query gets to an authoritative DNS server that provides the IP address.

3. Querying the Authoritative DNS Server

When one or more recursive DNS servers cannot find the requested data in their cache, they will attempt to locate it in other ways. After that, the request is forwarded to the next higher-up in the DNS hierarchy.

As long as no nameserver for the domain is found, the search will continue. It is the job of these root name servers to keep these records for the domains they serve.

4. Accessing the DNS Record

The authoritative name server can retrieve a domain name’s address record (A record). One way that the “A record” can be retrieved from the authoritative name servers is by using a Recursive DNS server.

The data is thereafter cached locally. The recursive server would know the response if another query asked for the “A record” for that particular domain name.

A time-to-live value, or TTL, is included in all DNS records and indicates when a record will be deleted. Eventually, the recursive DNS server will request an updated copy of the records.

A machine can get the “A record” from a Recursive DNS server, which already holds the data. After that, the file is saved to your computer’s memory.

At the same time, the IP address is retrieved from the DNS record and forwarded to the browser. The IP address listed in the A records will direct the browser to the server hosting the requested website. The total time it takes to do a lookup is no longer than microseconds.  

What Should You Know about DNS Difficulties?

Clearly, the Domain Name System is crucial to whatever actions you take on the internet. Therefore, your experience may deteriorate quickly if there are any issues with the system. So, what can go wrong here?

Inefficient DNS Server

To begin, your ISP‘s DNS servers can be a source of delay if they are inefficient or are not set up correctly for caching. This is especially the case when a page that incorporates content from numerous external sources is loaded.

When using the internet at home or at the office, switching to DNS servers designed for speed can significantly improve performance. How do you overcome the issue? Well, it is simple and all you have to do is go for companies that offer high-quality DNS services, probably with business-friendly add-ons.

The added benefit is that they can block access to sites that are known to be harmful. They do so at the DNS level, preventing them from being loaded in an employee’s browser. In this way, it is possible to block potentially offensive websites.

Similarly, parents can take advantage of DNS-based parental control systems to restrict their children’s access to mature or otherwise unsuitable information across all devices.

Local DNS Issue

In order to speed up responses to frequently used queries, your DNS server stores them in a cache and retrieves them without consulting other DNS nodes. Your computer also maintains a local DNS cache, which might cause problems when it becomes corrupted. There is no need to change DNS servers to fix this issue. Simply clearing your local DNS cache will do the trick.

Privacy Issue

Remember that your ISP’s DNS servers know about every domain name you’ve requested; unless you’re using a VPN. In most cases, it does not matter, and your ISP does not even care. But sometimes, some service providers use it to their advantage.

For instance, if you type in a domain that does not exist, your browser will be redirected to a search and advertising page with a query generated from the domain name.

Again, this might not appear to be a problem at first glance, but it could have serious implications for your personal privacy. What started out as a safe exchange of information between your browser and the DNS server is now at risk.

This occurs because your Internet service provider (ISP) diverts a copy of your request to an incorrect destination. So, you should not take it lightly, or it might lead to serious consequences, including the DNS ending up under attack.

What Are DNS Attacks?

Phishing is a type of social engineering attack often used to steal user data.

©Golden Dayz/Shutterstock.com

You have probably heard about phishing before. Criminal webmasters create a site that seems much like a legitimate one, such as PayPal, a gaming site, a bank, or a dating service. Using spam, fraudulent advertisements, or other methods, they spread links to the phony site.

If an unsuspecting user goes in without realizing it is a phony, they have just handed the bad guys access to their account. The fraudsters then use those credentials to log you into the legitimate site, where you remain unaware of the attack.

The address bar is the one and only giveaway for many scams. To avoid becoming a victim of phishing, it helps to keep a close check on the address bar. Sometimes, it is easy to spot the forgery, like a site that falsely presents itself as LinkedIn, but actually uses a completely unrelated domain name (like ABC.com).

Some go to greater lengths to trick you by using slightly different names like Paypel.com or incredibly long URLs to hide their true domain. But a savvy internet user will see through any deception.

Cache Poisoning

Speaking of DNS attacks, cache poisoning is among the most troublesome. As part of this type of assault, malefactors introduce false data into the DNS, usually by altering the cache.

When a user enters a legitimate domain name, the address bar displays the IP address for a fake site, since the DNS system has been poisoned. There would be no outward sign of sabotage; unless the criminals perform a particularly bad job of spoofing the intended site.

DNS Hijacking

Local DNS hijacking is also common and usually targets your machine. When malware is active, it modifies the system’s TCP/IP configurations to point to a malicious DNS server.

Obviously, this is only effective if the malware in question is able to bypass your antivirus software, but some people still have not gotten the memo about installing antivirus software on all of their computers.


A DNS server is a testament to the fact that today’s internet architecture has evolved significantly. These days, we have moved to a client/server network model in which clients start connections and servers react.

This is in part because the IPv4 address pool has run dry but also because of an architectural evolution that is needed to deal with the tremendous expansion in the number of devices in networks.

Things are surely getting better and more sophisticated in the DNS realm, but it is essential to understand that DNS is attractive for everybody – and we mean everybody! Those who make their living off the Internet are naturally quite curious about what people do on it.

Criminal behavior on the Internet is of essential concern to those agencies whose job is to police such behaviors because every crime is a cybercrime nowadays.

So, the DNS is always under attack. But, thankfully, new and improved security software solutions are becoming available to offer some peace of mind. The sooner your business realizes that DNS security is crucial, the better.

It becomes especially critical as you and your workforce become more reliant on remote access. You should think about making it a central part of your company’s network security solution once you have familiarized yourself with what it implies and how it will influence you.

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Frequently Asked Questions

How can you find your DNS server?

It is possible to find your DNS server in many different ways. Using a PC or router is the first choice.

If you are running Windows 8.1 or 10, click the Start button in the lower-left corner, type Command Prompt followed by ipconfig/all, then press Enter. After that, a plethora of computer-related details, including a DNS server list, will be displayed to you.

If you are using a Mac, go to the system preferences, then Network. To examine the DNS settings for a given network connection, select that connection, go to the Advanced button, and then pick the DNS tab. Your servers are displayed here.

Can you change your Linksys router's DNS server?

Yes, you can, but keep in mind that the process of changing the DNS settings is different for every router. It is also important to bear in mind that you must give your router a permanent IP address in order to modify its DNS settings.

If you have the Linksys router, you can change the DNS server using the following instructions:

  • Go to your browser and type, then log into your router’s web interface.
  • Now, go to Setup and proceed to Basic Setup.
  • Find the Static DNS 1 and Static DNS 2 options and add your preferred DNS servers to the fields.
  • The Static DNS3 field allows you to add a DNS server from a different provider, so leave it blank if you do not wish to change it.
  • Click Apply.

Are there advantages of using a DNS server in networking?

One of the most important discoveries that have propelled the world wide web for nearly three decades is the Domain Name System (DNS) server management, which holds the entire internet together.

The DNS server offers a number of benefits. For instance:

  • It is because of DNS that you do not have to memorize long and tedious IP addresses. Consider how inconvenient it would be if you had to learn the IP addresses of all the websites you use often, such as Facebook, Twitter, Google, and so on.
  • It improves the security of your work and home connections. Secure DNS servers are built to prevent intrusion attempts before they even reach your servers. That being said, you may have to take additional security measures, which is especially important for a large firm with a great deal of sensitive information to safeguard.
  • Some DNS servers help make it easier to explore the internet at a faster speed. As a result, they have extremely fast connections to the internet, which is a huge boon to the businesses and individuals who rely on them.

Are there disadvantages to using DNS servers?

Just like everything else in the world, there are some disadvantages to switching to DNS servers. For instance:

  • The fact that a single organization can only manage the DNS registry is one of the system’s major drawbacks. This international nonprofit has its origins in a single nation. This is a common criticism leveled at the principle of net neutrality during the past three decades.
  • A DNS query does not transmit client info, which is why cybercriminals often favor DNS for hacking and phishing. Instead, the server is only able to view the client’s IP address, which is easy to imitate by malicious users.
  • DNS servers operate on the basis of a master-slave architecture. If the primary server goes down or is tampered with, it won’t be easy to access any data or websites stored on that server. However, hackers have also utilized this to their benefit. They have found ways to phish information by attacking the server machine and redirecting users to malicious websites.

What can you do when the DNS server fails to respond?

The “DNS Server Not Responding” problem is a particularly frustrating reason for being unable to connect to the internet. It is like in that old fairy tale where the troll waits under the bridge and yells, “Thou shalt not pass!” before swallowing everybody who tries to cross it.

Well, it does not have to be that serious with DNS servers, and you can try a number of solutions.

First of all, you should switch your web browser. If you notice a problem with Opera, you may want to switch to Firefox or try Google Chrome to see if it works.

Check if you have recently tempered with any firewall settings. You may want to consider turning it off temporarily. Firewalls are essential for defending your computer against malicious DNS assaults, but they have a nasty habit of disrupting your Internet connection.

Clear all your DNS settings and try again. It is easy to clear your DNS cache and this usually resolves the issue quickly.

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