Understanding DNS (Domain Name System) is important because it determines if your business can send and receive emails and if your business’ website is visible to the world. This Tech Tip explains basic DNS terminology like domain names, name servers, DNS lookup and common DNS records like NS, A and MX. I believe that most small business owners should understand the basics of how DNS works. Any time you ask an employee or contractor to make changes that will affect your DNS records, you should be sure that this person knows what they are doing. Even if you aren’t a small business owner, I think you’ll find this overview of the DNS system useful.
Real World Analogy
Before I jump into DNS terminology, I think it’ll be useful to start by giving you a real-world analogy of what the Domain Name System is and how it works. DNS is like a phone book for the Internet. You remember phone books don’t you? Back in the 1990s, and before, people used to look up a person’s name in the White Pages to find that person’s phone number. Then they would dial that phone number to get ahold of that person. The DNS system serves the same purpose. When you type a website’s name, like soundsupport.biz, into your web browser you are initiating a DNS look up. Behind the scenes your web browser looks up the IP address for that website. Then your web browser uses that number to contact the web server which then sends the webpage to your computer. This lookup typically occurs in the blink of an eye. Now, let’s look at DNS in a bit more detail.
DNS Basics Explained
The 3 main components to the Domain Name System are:
- Domain names
- Name servers
- Individual DNS records
Let’s start with simple definitions for each and then I’ll illustrate how they work together.
Domain Names – A domain name is a human-memorable name registered by a business or person. Even if you’re not familiar with the term “domain name” you know what domain names are. Some examples 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 a business’ web site or email accounts.
The following example demonstrates how domain names, name servers and individual DNS records are tied together in a DNS lookup.
Each 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 soundsupport.biz into a number called an Internet Protocol (IP) address like 188.8.131.52. Thus, when you type soundsupport.biz, 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, soundsupport.biz. Next, the name server locates the www record for soundsupport.biz and its corresponding IP address. This IP address is sent back in response to your computer’s query. This query and response 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 replies by sending your computer a copy of the web page for soundsupport.biz. If everything is working properly, this entire process occurs in the blink of an eye. The only part that you see is the web page which appears on your screen after you type soundsupport.biz. This example gives you a glimpse into how DNS works.
If your company’s DNS records are not configured properly then DNS lookups could produce inaccurate results. If this happens, your company may either lose the ability to send and receive email messages or your business’ website may not be visible to the world. For most businesses either of these developments is a big deal. Thus, it’s important to understand a bit about the DNS system and to make sure that when you ask a person to modify your company’s DNS records the person understands how DNS works.
Types and Examples of DNS Records
For each domain name there are multiple types of records listed in the DNS system. The most common record types are NS records, MX records and A records. As an example, for my own domain name, soundsupport.biz, I have the following DNS records:
Let me translate each of these records into plain English.
The first record is called an A record. A stands for Address. It simply indicates that the IP address associated with soundsupport.biz is 184.108.40.206. In other words, this record tells your computer to contact the web server whose address is 220.127.116.11 in order to get a copy of the web page at soundsupport.biz.
The second record is called an MX record. MX stands for Mail eXchange. This record tells your computer to contact the mail server named mailfoundry.bigmountainmail.com if you want to send email to my Sound Support email address, firstname.lastname@example.org.
The third and fourth records are NS records. NS stands for Name Server. These records tell your computer that ns1 and ns2.hover.com store all DNS records for my domain name, soundsupport.biz. So, all queries that your computer needs to make for the sound support.biz domain should be directed to ns1.hover.com or its partner, ns2.hover.com
There are a number of other types of DNS records, such as CNAME, TXT, SOA, and PRT as well as other DNS-related terminology. If you need to learn about any of these types of records or terminology, check out the excellent DNS glossary at Men & Mice.
If you want to view the DNS records for your domain name you can do a lookup at DNS Toolkit.
Next week’s Tech Tip will include my DNS management tips to avoid common problems.
Some readers may also be interested in some of my previous, related, Tech Tips: