Issue No. 120August 2022
What is DNS?
The Domain Name System (DNS) is the phonebook of the internet. Although it provides a critical function, many people have never heard of DNS. Today we’d like to dive into a little-known aspect of the internet, explain the critical role that DNS fills, and detail what can happen when DNS goes wrong.
As we detailed earlier, DNS can be thought of as the phonebook for the internet. DNS bridges the gap between the way that humans interact with computers, and how computers interact with one another. To understand this a bit better, it is important to discuss a bit of the way that the internet and local computer networks function. Any device that is connected to the internet is provided with an IP (Internet Protocol) address. The IP address might be familiar to you, often these local addresses inside your home network look something like 192.168.1.10. This address is a ‘unique’ identifier for a network object (which is any device connected to the network) inside of a Local Area Network (LAN). Devices connected to the same network can communicate with one another through a variety of methods, and one of the most basic and effective is via their IP addresses. If you scale this concept up to the level of the internet, one surprising thing is that the communication occurs in much the same way. Websites have unique address identifiers which are referred to as a Public IP Address. Public in this instance means that the IP address is accessible via the internet. This should be familiar to most folks, who fire up their favorite web browser every morning to visit 22.214.171.124 to check the news, head over to 126.96.36.199 to check their email, and then check 188.8.131.52 to see what their commute looks like…right? My facetious example highlights just how critical a role DNS plays in our use of the internet. Those websites are, in order, nytimes.com, Gmail, and Google Maps. DNS is able to translate from something that is human readable, like www.nytimes.com, into something that a computer is capable of understanding, 184.108.40.206.
Outside of telling your computer the address of a website you’re looking to visit, DNS plays many other critical roles in the way the internet works. Email, for instance, is dependent on something called an MX Record. This is a DNS entry that tells an email client where to deliver email—whether its for your corporate email server or your private Gmail account. A multitude of other types of DNS records serve additional important functions—redirecting traffic from one website to another, providing public access to internal company resources, or verifying that you own a particular domain. As you may have guessed based on some of these descriptions, when DNS functions properly you’d never notice it was there. When it doesn’t, however, things get squirrely quickly.
DNS is ‘provided’ by DNS servers. This could take the form of an internal one at your corporate office, or a publicly accessible one like those provided by Google, Amazon, or Cloudflare. Setting your computer’s DNS to one of these publicly available DNS servers means that your computer is somewhat beholden to however that computer ‘resolves’ DNS. DNS Resolution is how a computer determines the IP address that corresponds to a URL, or vice versa. When this process goes awry, all sorts of strange behavior can crop up. As a recent example, an issue occurred with Google’s public DNS that was pointing US based Outlook to a mail server in Australia. Although that server was still owned and operated by Microsoft, the increased latency of an overseas connection played havoc with those who were affected. You may recall back in July of 2021, there was a massive internet outage affecting companies like UPS, FedEx, AirBnB, and Fidelity. This was all due to a DNS outage at a large security firm called Akamai.
In summation, DNS is a critical and oft-overlooked piece of the internet’s backend infrastructure. From allowing for the flow of email, to directing you to the correct website for the latest funny cat video, DNS is completely essential. Ensuring that DNS is properly configured for your organization is an important role for any IT provider to fulfill. If you have questions about this or any other technical item, please reach out to Kazmarek Technology Solutions.