The Domain Name System (DNS) is what facilitates the widespread internet usage we have grown accustomed to today. Everything that connects to the web uses DNS, which translates domain names into numerical addresses that machines can read. And while it might seem like it, DNS doesn’t run on invisible wires or airwaves like radio does. It requires a physical location in order to work. This location is a server— or more accurately, thousands of individual servers positioned all across the world that essentially make up one huge, intricate network. If we could actually “see” DNS in action on a global scale, it would probably look a lot like a spider web.
In this resource, you’ll learn all about the DNS server.
Tip: Need a deeper understanding of what DNS is or does? Visit our DNS Explained video, which breaks it down in a fun way that’s easy to understand.
A DNS server is a device or application specifically designed to help other devices and resources connect and communicate with one another on the internet. There are client-side and server-side models, which all work together to get the end-user to their desired online destination.
The main types of DNS servers are recursive, authoritative, top-level domain (TLD), and root servers. Each one is needed for internet requests to be completed successfully. Recursive servers, also called resolvers, are what answers each initial query made from a user’s device. Unless a recursive server has cached information on a website, it must contact another server for an answer. This is called a DNS lookup process, which is similar to how you would look up a number in a phonebook.
The first step in the process is for a recursive server (typically that of your internet service provider) to contact a root server, which is the nameserver that holds all the details on TLDs for a specific region. Once it accepts a query from the recursive server, the root sends the recursive server to the appropriate TLD server. A TLD nameserver is what houses the information on domain names with common extensions (.com, .org, .gov, .edu, etc.) The TLD server then directs the recursive server to an authoritative nameserver, which is typically the server that provides the final answer for a query. Authoritative servers store the most up-to-date DNS records for a domain and are the servers used by DNS providers.
The term client-side entails all web-based activity that occurs on a user’s device. Every modern computer, smartphone, tablet, and gaming console, for instance, utilizes a client to access the internet. The most common client the average person uses to access the internet is a web browser, such as Chrome, Opera, Edge, Firefox, Safari, Internet Explorer, DuckDuckGo, etc. Browsers and other clients rely on DNS to connect to websites, programs, or to other servers. In order to reach a website or service, a client-side device must first go through a recursive resolver.
The server-side represents the web servers or applications that have access to the information needed to facilitate online transactions. These servers are what handles all client requests, as well as back-end operations and maintenance-related tasks. When you configure your DNS, it’s the server-side that houses the details.
Each device that connects to the internet has to have an address in order to be found online. These are are internet protocol (IP) addresses. The most widely used IP format is IPv4, which is a 32-bit address. There are limits to the availability of IPv4 addresses, however, which is why IPv6 was developed. Version 6 of the internet protocol is a 128-bit address and allows a near-infinite amount of IP addresses to be created. DNS A records are configured using IPv4, while AAAA records correspond with IPv6 addresses.
Whenever someone types a URL into their browser, a DNS lookup process is initiated. This typically involves the servers mentioned above, but queries can end at a user’s browser or the recursive resolver if the IP address is in cache. A DNS cache is like a memory bank for website information.
If you have visited a site recently, there’s a good chance your browser can return the query directly. If the site is not in cache or the time to live (TTL) of the DNS records for a site has expired, your browser will contact a recursive resolver, which will go through the lookup process until the new information for the website is found.
Occasionally, you may try to access a website and get an error message stating that the DNS server is not responding. There are numerous reasons for why this happens. Some examples are an internet service provider (ISP) is having issues, a DNS provider is experiencing an outage, or there’s a problem with the actual website you are trying to reach. However, this can also be caused by something client-side, such as a firewall or antivirus conflict, a browser-related problem, or a custom DNS configuration set up by the user.
An easy way to check if the issue is client-side is by trying to access another website, switching to a different web browser, temporarily deactivating your firewall or antivirus, rebooting your router, or using your computer’s network troubleshooting feature. If the issue is server-side, you will be unable to access the site(s) affected until the issue is resolved by the domain owner, ISP, or the DNS provider.
Without DNS servers, we would be unable to access anything online. The Domain Name System requires servers to answer queries and carry out client requests. The different types of servers are recursive, root, TLD, and authoritative. Each of these servers has a distinct purpose within the DNS lookup process, and are necessary for the internet to operate the way it does today.
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