Every computer on the internet has an assigned Internet Protocol (or IP) address. IP addresses are a series of four number separated by periods, and usually appear in the following format: 45.208.359.88. IP addresses allow computers to send information across the internet to a specific recipient. While these numbers are easy for computers to read, they can be confusing for humans to memorize. Instead, we use Domain names to access websites (www.minterest.com, www.yahoo.com). The system that translates these human-readable domain names into machine-readable IP addresses is called Domain Name System (DNS). But how do all these names and numbers connect? The answer is through a series of DNS steps.

DNS From Start to Finish

Think of DNS as a pyramid. As the user/client you’re standing on the foundation. The next level is achieved when you make a DNS query (inputting a web address). After that, your Internet provider sends the query request to the DNS name servers (like .com, .net, etc. servers). From there, you finish your journey to the top. The name server sends the query to the root servers for the correct location.

For instance, here’s what happens when searching for abcstore.com:

You, the user/client, types in abcstore.com into the web browser.
Your Internet provider seeks out the .com server.
The .com server goes to the root server.
At the root level, the DNS query is directed to abcstore.com and it comes up on your browser.

Now, DNS Resource Records are important to know too. They are the response to a DNS query and there are several different types.

Common DNS Resource Records

Individual DNS records provide instructions on how to direct specific internet traffic. Each Resource Record performs its own specific function and directs certain data to certain IP addresses. For example, three common DNS records include: A Records, CName Records, and MX Records.

A Records are known by another term – the ‘host address.’ This is because when a query is made (like typing in a web address), an A Record points that domain name to the IP address of the system that hosts the domain.

As for CName Records they are known as an ‘alias.’ Unlike the A Records, CName records cannot point to IP addresses. Its function is to point clients to another record for a query answer.

MX records are often referred to as the ‘mail exchange.’ An MX record defines the incoming SMTP server for a domain so mail servers know where to deliver email within a particular domain.

Other DNS Resource Records can include ones for reverse mapping pointers (PTR), text (TXT), Nameservers (NS) or service records (SRV).

Understanding DNS Zones

All of this DNS data is often divided into manageable sets called ‘zones.’ These zones include name and IP address information about one, or more, parts of a domain. An authoritative server for a domain contains all of the information for a zone. However, zone data is often stored on servers other than the authoritative server.

These ‘secondary servers’ allow owners to balance the demand on servers, but also provides a backup in case the primary server fails. Now there are four key types of ‘zones’ – Primary, Secondary, Stub and Forward, with each performing a particular function:

Primary Zone – Sometimes known to as ‘master zones,’ these can also contain subzones that include resource records like alias (CNAME), host address (A), or reverse mapping pointer (PTR) records.

Secondary Zone – These are called "slave zones" since they load zone data from a primary server or another secondary server.

Stub Zone – These are much like a secondary zone, except they only transfer the name server (NS) records for that zone.

Forward Zone – As the name implies, this zone ‘forwards’ all queries for that particular zone to other servers.

As you can see, DNS is far more complex than just a resource used to surf the web. It’s filled with many interesting facets. But hopefully this gives you the proper introduction into how DNS works and how it can serve you.

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