Understanding DNS (Domain Name System) is important because it determines if you can send and receive emails and if your website is visible to the world. This quick article explains basic DNS terminology like domain names, name servers, common DNS records like A, MX and NS and DNS lookup.


The 3 main components to the Domain Name System are:

Domain names
Name servers
DNS records

Let’s start with simple definitions for each.

Domain Names – A domain name is a human-memorable name registered by a business or person. Some examples of domain names are:


Name Server – A name server is the server that stores individual DNS records for a domain name. Each domain name is assigned its own name server.

DNS Records – Individual DNS records list the IP address (aka IP number) of the specific server that stores your web site or email accounts.


For each domain name there are multiple types of records listed in the DNS system. The most common record types are A records, MX records and NS records.

A Records – A records or address records assign an IP address to a domain name.

MX Record – MX records or mail exchange records create a mail route for a domain name. A domain name can have multiple mail routes and each are assigned a priority number. The mail route with the lowest priority number identifies the server responsible for the domain. Other mail servers listed with higher priority numbers are used as backups.

NS Records – NS records or Name Server records tell your computer or mobile device where all of the DNS records for your domain are stored.


The following example demonstrates how domain names, name servers and DNS records are tied together in a DNS lookup.

Every time you visit a web site you use DNS (Domain Name System). The Domain Name System’s basic job is to turn a website address like www.borealiscomputing.com into a number called an Internet Protocol (IP) address like When you type www.borealiscomputing.com, your computer queries the DNS system to determine the corresponding IP address for that website.

The DNS system initially locates the name server assigned to the domain name, borealiscomputing.com, then locates the www record for borealiscomputing.com and its corresponding IP address. This process is called a DNS lookup. After the DNS lookup, your computer sends a request to the web server at that IP address. The web server then sends a copy of the web page: www.borealiscomputing.com. If everything is working properly, this entire process occurs instantaneously and you see the home page of the domain www.borealiscomputing.com. This example gives you a quick look at how DNS works.

If your DNS records are not configured properly then DNS lookups could produce inaccurate results. If this happens, you may either lose the ability to send and receive email messages or your website may not be visible to the world. That’s why it’s important to understand a bit about the DNS system and to make sure that when you ask a person to modify your DNS records the person understands how DNS works.