Differences between Unicast DNS and Anycast DNS

Unicast DNS and Anycast DNS are both great ways to route the incoming traffic. Let’s see what are their differences!

Unicast DNS – Definition

Unicast DNS is a traffic routing mechanism that operates in a one-to-one way. The information is transferred from its source node to only one specific destination. The receives and the sender are the only participants in the particular communication in the selected route. Therefore, Unicast DNS is an impressive solution for the transportation of information on the Internet. 

Anycast DNS – How does it work?

In addition, Unicast DNS is capable of routing DNS queries among DNS servers and DNS users. As a result, the information for a particular domain and its IP address is stored only in one server. Therefore, every incoming request has to travel and reach that server to receive an answer, regardless of its geographical position. That means when a user is near the location of the server, and its response is going to be way quicker. However, in case the user is at a distance from the server, the response is going to take more time, and probably it is going to experience latency.

When we are analyzing Unicast DNS and Anycast DNS, there is no doubt that Unicast is cheaper and easier to use. The reason for that is it includes maintaining and monitoring only one server. However, it is a great option for local businesses. Yet, the availability of your domain relies only on that specific DNS server which could be a huge risk if it fails for some reason. 

Anycast DNS – Definition

Anycast DNS is a mechanism for routing the traffic and achieving fast delivery of content from the websites. It utilizes singular IP addresses on several DNS servers. To put it another way, a single IP address but used by all the nameservers that are on your DNS network.

The purpose of implementing Anycast DNS is to have servers in various places all around the world to be as near as possible to your potential users. This is extremely valuable for Anycast DNS clients because the most nearby they can have a server to their end-users, the quickest their requests can be answered to. It depends on the location from where the user initiated the request for the website, and the nearest available server is going to resolve it. That way, users are able to explore your website without any unnecessary waiting time.

In addition, if the closest DNS server is down for some reason or under attack, the second one, which is closest to the user and available, is going to resolve the request. That means your website is still going to be reachable for your users, and because Anycast DNS uses the shortest route, your domain’s resolution time is pretty fast. 

Unicast DNS and Anycast DNS – Comparison

When we are comparing Unicast DNS and Anycast DNS, it is required to mention the DNS recursive server, which is the one obtaining the DNS records for the demanded hostname. The process usually involves a large number of DNS servers. 

In Unicast DNS routing, the DNS recursive server is going to request the data from the first DNS server on the list, pause till it responds, or there is a timeout, and then it will be capable of asking the following server. For sure, that could cause high latency.

In Anycast DNS routing, DNS recursive servers are configured with an individual IP address for every blend of DNS servers. As a result, the latency is reduced, and there are no pauses when a recursive server queries a DNS server that does not respond. 

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