Anycast DNS and Unicast DNS: Contrasts & Comparison

Let’s examine the differences between Anycast DNS and Unicast DNS!

Anycast DNS

Anycast DNS involves multiple name servers that are positioned in different locations all over the world. All of them store and are able to provide the same IP address. Anycast DNS routes the users’ DNS requests to the nearest and available server. 

Unicast DNS

Unicast DNS includes just one name server holding the IP address and all of the DNS data (DNS records) of your domain name. That means all of the DNS requests are routed to this specific name server. Additionally, the location of the user does not matter because only this single server can provide the needed DNS information.


Anycast DNS and Unicast DNS have one major contrast.

Anycast DNS: The DNS resolver responsible for obtaining the DNS data for the requested hostname is configurated with one Anycast IP address for a particular group of name servers. That reduces the latency, and there are no delays because of non-responsive name servers. In addition, thanks to Anycast DNS, Points of Presence (PoPs) that are unreachable are automatically excluded, and the DNS resolver is directed to the closest best performing DNS server.

Unicast DNS: The DNS resolver could request the needed DNS data from a lot of different DNS name servers. It usually asks one of them and waits for its response, or there is a timeout. Only then the resolver proceeds and asks the second server. Therefore, that has the potential to create high latency. 

Anycast DNS and Unicast DNS: Comparison

Let’s compare Anycast DNS and Unicast DNS based on several criteria and factors. That way, you can easily understand which one is the preferred choice for you, and it is going to fit your needs.

Simple to implement: Using and installing Unicast could be easier due to the fact it involves one machine and one IP address. Yet, the incorporation of Anycast DNS is also not so difficult. In addition, with Unicast DNS, you are required to maintain an individual server. On the other hand, configuring several servers with Anycast DNS means a little bit more effort.

Safety and Security: It tends to be a little bit more risky to hold just one server with all of the DNS data (DNS records). If it crashes or it is under attack, you could experience losses. All of your clients are not going to be able to reach your website, which affects in a negative way your reputation and finances. When you implement Anycast DNS, you have multiple servers that can answer users’ requests. That means even if one of them crashes, the others will still be able to handle the incoming traffic.

Response time: If your visitors are waiting too much for a response, it won’t be a surprise if they leave your website. Even without exploring your website content! On the other hand, Anycast DNS acts quickly and significantly improves the response time.

Target market: Unicast DNS is a great choice, and it is going to fit perfectly anyone that offers services and products in a local market. Yet, if you want your business to grow, or you are operating already on a multinational level, then you should choose Anycast DNS.

List of DNS Terms You Need to Know

Here is a list of some DNS terms that are essential for you to know and understand. They are going to help you manage your network more easily and be familiar with the terminology. So, let’s explain a little bit more about each one of the DNS terms!


The Domain Name System, or DNS for short, is a worldwide naming database. It translates domain names to IP addresses (IPv4 and IPv6). DNS is created with several levels in hierarchical order, and it is entirely decentralized. Thanks to it, we are not required to remember long and complex numbers (IP addresses) for each website. Instead, we use the domain names. 

DNS server

DNS servers are two different types – authoritative name servers and recursive name servers.

  • Authoritative name servers – They store DNS zones with zone files for the domains and answer DNS queries. Examples: TLD (Top Level Domain) servers and Root servers.
  • Recursive name servers – They travel and ask different servers for an answer to the DNS queries.

DNS zone

The DNS zone is a small segment of the DNS namespace. Every zone could be maintained by a separate DNS administrator. That is why the Domain Name System is decentralized. Domain and zone are not the same things. A domain could hold a single DNS zone, or it also can have several. 

DNS record

A DNS record is a simple text file that indicates an instruction for a domain. There are various DNS record types that have different purposes.

For instance, one shows the IP address (A or AAAA record), another shows a service, such as an email server that receives emails (MX record), and so on. 

DNS query

The DNS query is the behind-the-scenes process of obtaining different DNS records of a domain, such as searching for the IP address (A or AAAA record). Users generate DNS queries when they want to visit a particular website.

Anycast DNS 

Anycast DNS is a routing mechanism that speeds the DNS resolution process. It performs by setting an identical IP address in multiple name servers placed in diverse geographical locations. As a result, when a user makes a DNS query, it is going to receive an answer from the closest and available name server. 

Dynamic DNS 

Dynamic DNS is implemented for automatically updating your IP address every time it changes. In the most common scenario, the Internet Service Provider (ISP) switches your IP address to a different one. The reason for that is simple. They hold extensive networks, and such action helps them for easy management. It is a great idea to implement Dynamic DNS in case you have CCTV cameras for surveillance. 

DNS cache

DNS cache is a useful mechanism for storing DNS data (DNS records) of domain names that are previously queried. A lot of different devices use such cache memory mechanisms, for instance, mobiles, computers, tablets, and DNS recursive servers. The main goal of DNS cache is to reduce the needed time for resolving a domain name. Due to the implementation of such a mechanism, DNS recursive servers do not perform the entire DNS lookup process each time a specific domain name is requested. 

DNS propagation

DNS propagation refers to the amount of time that is needed for your new DNS changes to spread through the entire global network – the Internet. For instance, if you modify a DNS record (A or AAAA record) and change the IP address for a particular hostname. Usually, the DNS propagation process takes a couple of hours up to 72 hours to spread the new information in each server all around the world.