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What Are Anycast DNS Servers?

Anycast DNS is an innovative addressing system that connects multiple servers with the same IP address. This allows users to access their resources from the closest server, making it more efficient and faster than traditional methods.

Anycast DNS is becoming increasingly popular among enterprises and service providers due to its many advantages, including improved performance, reduced latency, and easier management.
By choosing Nominus as your partner in registering a domain, you can also get the additional benefit of leveraging Anycast DNS servers to ensure fast response times and free access to every user worldwide. Learn more about this amazing technology today!

What is a DNS server?

Breaking the term "Anycast DNS servers" into its components can give us more insights into what it is and how it works.
When you type in a domain name (like, your device reaches out to a DNS server to figure out what its IP address is. This is called “resolving” a query or resolving a domain name. If you typed in the IP address instead, you would bypass the DNS server and directly connect with the website.
Anycast is a network addressing and routing method. It’s typically compared to unicast and understanding one can help you understand the other.

Anycast vs. Unicast

In order to understand unicast, consider a website that's hosted on a server residing in Australia. No matter where in the world you are, when you access this website from your device, you will be routed to Australia. If you access the website from New Zealand, which is relatively close, there will be limited latency or delay thanks to proximity. But if you access the website from Iceland, which is quite far away from Australia, there might be more latency (assuming there is no other difference). This arrangement also makes the servers more vulnerable to attacks that aim to overwhelm the system with traffic because there is a single point of failure. This is unicast, where if a device reaches out to the internet with an IP address, it will be connected to a specific server in a specific location.

Anycast, on the other hand, connects one IP address to multiple servers in multiple locations (called nodes). If you are trying to access a website with multiple servers and Anycast routing is in place, you may be connected to the node in the best position to serve you. It's determined by proximity and how much traffic a node/server handles at any given time (among other things). Let's say there is a website hosted on 26 nodes across the globe named from A to Z. You access this website before, during, and after a flight.

  • You may connect to node M before you take off because it’s closest.

  • When you access the website during the flight, you may connect to node Y because even though X was closer, it managed all the traffic it could handle, and you were routed to the next best node.

  • When you land and visit the same site, you may connect to node B because it is the closest.

This allows the Anycast system to be faster, more efficient, and even more resilient because even if one or a few servers are down, the traffic is routed to the other servers that are best positioned to cater to your needs.

How Does Anycast DNS Work?

The Anycast DNS works on a layer prior to the servers hosting a website since the DNS servers don't host website data but rather the information that helps devices connect to the right server (IP addresses).
And even though Anycast DNS essentially works on the same principle, there is more to it than simply finding the best possible DNS server match. First, let’s understand how a typical DNS system gets you the right information - the IP address for a domain name you enter in your device’s browser.
When you type a domain name, say, in your browser, it automatically reaches out to a DNS resolver or Recursor since it has the job of resolving the client's query.
Then the steps are as follows:

  1. If the IP address is already in the cache of the DNS Resolver, it will directly answer you. That usually happens if someone using the same ISP has already visited

  2. If it’s not in the Resolver cache, the DNS Resolver will reach out to a Root Server top of the DNS hierarchy. It doesn't know the IP address of, but it knows which servers keep the record for all .org (or .com, .net, etc.) websites and their IP addresses. They are called Top Level Domain Servers or TLD servers.

  3. The Resolver then asks the right TLD server for the information. It doesn't know the IP address as well, but it does know which Authoritative DNS Servers or Nameservers (third in the DNS hierarchy) know the actual IP address and passes the information to the Resolver.

  4. The Resolver gets the actual IP for the website from the Authoritative DNS servers and passes this information along to the client, i.e., your device/browser.

If the routing is unicast, your device (the client) will reach out to a specific DNS resolver whenever it has a query. If the Resolver is experiencing a lot of traffic or is too far away, there will be latency. But in an Anycast routing configuration, the device will connect to the best possible DNS resolver for query resolution. This is typically determined based on location (for minimal latency, which in turn is identified by network topology (though there might be other rules in place).

The image above shows the difference between Unicast and Anycast DNS routing techniques. In Unicast, a device might connect to a specific resolver by default. Whereas in Anycast, the device has access to multiple resolvers, and the most optimal one is chosen to resolve its query.

However, anycasting is not limited to the resolver layer. It can be applied to other layers as well, including DNS root servers.

Anycast DNS Server Benefits

There are several reasons why Anycast DNS servers are desirable and an asset to businesses across the world, regardless of their domains.

  • Increase performance: Low latency is the most obvious benefit, and even though it's an end-user benefit, it has far-reaching implications. Because even if high latency isn't a reason loyal customers stop engaging with the web services of your brand, it reflects in satisfaction numbers and may throttle the number of new customers. Anycast DNS can go a long way toward improving this situation.

  • Improved reliability: Anycast DNS servers offer more resilience against DNS DDoS attacks (Distributed Denial of Service attacks) like DNS amplification attacks, which made up a significant portion of the 9.84 million DDoS attacks in 2021.

  • The automatic load balancing ensures better DNS server load management and results in improved reliability and a reduction in potential downtime.

  • Easier Management: With a single IP address for multiple servers, managing your DNS infrastructure is simpler and less error-prone.

Anycast DNS can be a positively impactful choice as a business and one that you might consider making before an existing vulnerability that Anycast DNS could have prevented becomes a liability.

Anycast DNS Examples of Implementation

Some of the largest organizations in the world have already gone through the Anycast DNS implementation phase. This includes:

  • Hulu completely redesigned its DNS architecture and built a dynamic Anycast DNS system from the ground up.

  • Google uses Anycast routing to direct queries to the nearest public server.

  • Amazon uses Anycast to improve/enhance availability and performance.

Nominus - The Domain Registration Partner That Offers Free Anycast DNS

Nominus is a trusted domain and trademark registration partner that offers its clients access to over 200 ccTLDs (roughly one-third of the total ccTLDs pool) and more than half - of 850 gTLDs. Anycast DNS is a standard part of our domain registration, provided through Cloudflare, one of the largest providers in this domain. With daily 10,500 main ISP connections, a presence in 270 cities in a hundred countries (including Mainland China), and 95% of the human population just 50 ms away from Cloudflare reach, its Anycast DNS can be game-changing for your business.