The concept of the Domain Name System (DNS) can be a confusing subject even to skilled and experienced system administrators. DNS is the system used to abbreviate Internet Protocol (IP) addresses, which are in the form of numbers, to memorable, user-friendly names. These Domain names address systems on TCP/IP networks (e.g. the Internet) by certain Web applications, such as browsers. This system enables computers to communicate using numeric addresses and computer users to use simpler names, for example, “www.google.com” and “www.yahoo.com,” to call up services, including websites and email servers on the internet.

How Domains and the Domain Name System Work

When you type a domain name into your browser’s address bar, your computer (or client) sends the name to a publicly accessible computer called a DNS server. This server contains a database mapping of human-readable names to their corresponding numeric addresses. The DNS server sends back a response to the client computer and informs it of the IP address of the target system you would like to access, thus enabling it to send the request directly to the target. Through a process known as recursion, the DNS server may also request the IP from other DNS servers.

Subdomains Explained

Registration of a new domain name for each new service or department in your organization would obviously lead to substantial costs and maintenance overheads. Fortunately, you can avoid this situation. Subdomains are relatively independent domains that are part of a larger domain. For example, ‘mail.domain.com’ is a subdomain of ‘domain.com’. Typically, organizations use subdomains to separate their different departments or enable separate but related services on the same domain.

About Name Server (NS) Record

Armed with an understanding of how DNS, domains, and subdomains work, it is easy to understand the concept of the name server or NS. When an organization wishes to register a domain, it acquires the services of a domain registrar, most likely either its Internet service provider or its web hosting company. They then check and register the domain name on their DNS system. This system then “propagates” or sends the DNS records related to your domain to the rest of the DNS servers throughout the globe. The provider’s DNS system address is listed as the NS record for the organization’s domain. This means that it is the authoritative system with regard to any changes to the status of the organization’s domain. This also means that the organization is able to assign subdomains to different name servers.

How to Check Name Server Records

Occasionally, you would need to find out the name server records for a particular domain. You can easily accomplish this task by using NS records tools that query DNS records. An NSLOOKUP is a command-line tool used by network administrators, and it requests information about DNS records for a particular domain. A forward lookup receives the domain name or subdomain and returns its corresponding IP address. To carry out a reverse lookup, you have to enter the IP address, producing the domain name or subdomain. You can see how such a DNS tool works in the video below.

This video is part of our Monitoring Video Tips series.

How to Get the DNS Server Response Time

You may also need to know the DNS server latency, that is, how long the server takes to serve up IP lookups. This affects the speed at which a particular system can be accessed. A useful NS records tool available for system admins is a tool that can record the request-response times and thus help you select the best DNS server for use on your network and provide your organization and clients faster access to online services.

If you want to see how the different DNS tests work, try them out for yourself in our Test tools section.