What is a DNS server?

We explain what a DNS server is, how it works and how to avoid DNS hijacking

Networks servers

Widely considered the backbone of the World Wide Web, Domain Name Servers (DNS) are a lot like a rolodex, in that they hold vast amounts of detail that are integral for websites and domains to run. It's thanks to DNS that devices like laptops, desktops and tablets can be connected to whatever website a user wants to visit. 

Similarly, you may have come across 'NS', which are nameservers, particularly when switching hosts while running a webpage. NS falls under the umbrella of DNS and holds an important role in hosting. It focuses on handling queries about server location offered by DNS, which makes it possible to use domains instead of IP addresses. 

When is a DNS server used?

When you open your web browser, and type in a website's URL, a DNS resolver will begin a scan of the web in order to identify the IP address of the domain you're after. The resolver works out the location of the stored information by examining one DNS server at a time.  

When the resolver finally pinpoints the location of the IP address, it allows for content elements to filter through to the user, who can then start to see the website as it is intended to be viewed. The content elements may include various types of user interface (UI), such as images and pages or other visual objects. 

How is the DNS server set up?

Internet Service Providers (ISPs) normally run their own DNS with a router serving as the gateway between a device and the DNS. IP queries are sent to the ISP’s DNS that look for where website assets are kept.

Are some DNS servers faster than others?

The pace at which queries can be resolved is heavily dependent on the location of a DNS server, and being further away from a server may mean that connections and responses will be slower. That is why the majority of ISPs make sure to have their DNS servers distributed across the globe, so that their customers can find themselves near one whenever they need to power up their websites.

Another aspect worth considering is the distance between organisations’ sites and their visitors. Although not always apparent, those who live closer to where the site is located experience a service faster than those based on the other side of the world.

One way to speed up the DNS lookup is to have already visited a page before. This is because the IP address and hostname will have already gone through the resolution process, meaning that the information will be stored on the users’ devices. Hence they will not be forced to search for the connection from scratch when they enter the name of the website into the address bar.

Another way to resolve speed issues is by using a content delivery network (CDN). These aim to deliver content faster when resolving queries, although it’s not considered a solution directly affecting the DNS. CDNs work by placing content into a location within a local proximity to the user visiting the website. Even if the DNS takes a while longer to resolve, the entirety of the content, such as the pictures and assets which comprise its UI, will be delivered to machines faster due to the considerably shorter length that they have to travel.

DNS server security concerns

A man maintaining servers

Shutterstock

Sometimes, DNS servers can be hijacked by hackers, leading unsuspecting victims to fake websites that appear to be the site you're trying to reach, but the IP address has been changed to appear as though it's the genuine site.

To avoid falling victim to such scams, you should ensure your antivirus and malware detection tools are up to date and if you see an invalid certificate warning message, it's a good idea not to head to the website, especially if it's asking for sensitive information.

What happens when a DNS server fails to respond?

There are occasions when you try to link a device to your network and find that it can't establish a connection - you'll be met with a "DNS server not responding" message. This can happen for a number of reasons, but there are also plenty of ways to fix this specific issue. It's normally caused by problems on the user's end, rather than faults server-side. It may well be the result of an issue with network connection, misfigured DNS settings, or a browser that needs an update. 

The error message also comes up for temporary server outages. You could, in theory, fix the issue by switching to another browser, particularly if the one you are using needs updating. Or, you can try disabling connections, changing your DNS server, or even flushing the DNS cache.  

If you are met with the message: "your computer appears to be correctly configured, but the device or resource (DNS server) is not responding", you can use a number of hacks. First, make sure that the proxy server is disabled in your browser settings, and also that your PC's power-saving settings are off. You may also try changing your network settings so that the device selects the DNS server automatically. 

For the Windows 10 version, you need to navigate to the Network and Sharing Centre, click the name of your Wi-Fi connection and select 'Properties'. From here you need to find 'Internet Protocol Version 4' and choose 'Properties' a second time. Then select options 'Obtain an IP address automatically' and also 'Obtain DNS server address automatically. And, finally, return to the list and find 'Internet Protocol Version 6', open properties one last time and do the same. 

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