DNS lookup: How does it work?

A DNS lookup, in a general sense, is the process by which a DNS record is returned from a DNS server. This is like looking up a phone number in a phone book – that is why it is referred to as a “lookup”.

What is a DNS lookup?

A DNS lookup, or DNS record lookup, is the process through which human-readable domain names (www.google.com) are translated into a computer-readable IP address (192.168.2.1).

It is the query journey initiated each time you enter a URL into your web browser’s address bar. Your DNS recursive resolver, also known as a recursor or resolver, will first check to see if the requested information is in a cache. If no information is available in the cache, the resolver will then request the IP address from the root, TLD, and authoritative nameservers.

Once the IP address has been found, the resolver will return that information to the client (your computer) in the form of the web page you’re trying to reach.

Importance of DNS Lookup

DNS lookup is a crucial component of internet communications, as it enables the seamless conversion of human-readable domain names into their respective IP addresses required for data transmission.

This process functions like an internet phonebook, allowing users to easily access websites and online resources through memorable domain names, while the underlying systems, such as browsers and servers, utilize the corresponding IP addresses to establish connections and exchange data.

By simplifying the website access experience for users and streamlining internet traffic, DNS lookup significantly contributes to the overall efficiency and user-friendliness of the internet as we know it.

How does it work?

The Domain Name System (DNS) is a series of servers located all around the world that store the configuration information of a domain name to make the process of converting a domain name into an IP address or other DNS configuration information more easily access a server.

There are 4 different types of DNS servers involved when performing a DNS lookup. Each DNS server type has a different role to play and may not all be required under certain circumstances.

• Recursive Resolver – This is the DNS server that your computer or device communicates with. This DNS server is typically issued to you automatically by your service provider and is geographically located nearby to return results as fast as possible. This server will cache DNS record data to speed up future DNS lookup requests.
• Root Nameserver – The root name server is responsible for returning the IP address of the TLD nameserver. For example, when resolving example.com, the root name server will return the IP address of the TLD name server responsible for .com domain names.
• TLD Nameserver – The Top Level Domain (TLD) name server is responsible for returning the authoritative name servers for all domains under the TLD it is responsible for. The .com TLD name server will return results for example.com but not example.org.
• Authoritative Nameserver – This is the DNS server for actually storing the DNS configuration data of a domain name.

What is it used for?

A DNS lookup is helpful for:

• Understanding your DNS configuration: You can use DNS lookup data to expand your knowledge of all your web properties. A thorough list of your digital properties can help you avoid “dangling DNS records.” Dangling DNS records belong to pages that no longer exist, but their DNS records still do. You should know that these records and related setting misconfigurations can lead to vulnerability exploitation.
• Monitoring third parties: You can use DNS lookup information to monitor the configurations and potential anomalies in third-party suppliers’ or partners’ DNS records. Failure to address DNS record misconfigurations or delete unused DNS records can put you at risk.

How do you do a DNS lookup?

Most of the time, a DNS lookup is something that you do not need to worry about as your operating system, or web browser, will handle this for you automatically when you need to resolve a domain name.

Many operating systems include a DNS lookup tool for performing DNS lookups manually for diagnosing problems. Windows systems provide a command line tool called nslookup and Linux and Mac systems include the powerful dig tool.

As an online alternative, all you need to do is simply enter the domain name that you want to perform a DNS lookup against and the results will be displayed right in your web browser. This provides even novice users with an easy-to-use DNS lookup tool.