Anycast DNS DNS Routing method

Anycast DNS and Unicast DNS: Differences

Anycast DNS explained

With Anycast DNS are established several servers, each of them in a separate geographical location, and they all can provide the same IP. Therefore, the DNS data about your domain name is duplicated on several servers.

The closest DNS server answers the request of the user. If one of the servers is not functioning, the next closest and available DNS server will answer the request. As a result, factors such as loading time, waiting for a response, and the users’ overall experience are a lot better.

Anycast DNS advantages

  • Better uptime and accessibility. One server can malfunction, however for several servers, it is unusual, at least not simultaneously. Therefore, higher uptime is guaranteed, and users can access your website at any time.
  • Better response time. The faster the response from the servers is, the less is the waiting time.
  • Improved security. You have several servers to rely on in case one of them gets compromised.
  • Improved SEO. Search engines recognize positive user experience and rank your site better.

Anycast DNS disadvantages

  • The process of configuring several servers requires more effort but is worth it.
  • The experience of having more than one server responsible for your website could be a bit expensive. 

Unicast DNS explained.

With Unicast DNS, the IP of the website can be found on only one server. All of the DNS data is stored just on this server. It doesn’t matter what the user’s location is. This particular server will answer the request. In case the server that holds the website data is near to the user, then he will receive a quick answer. But in the other scenario, when the user is far away from the server, the response time is going to be a lot longer. 

Unicast DNS advantages

  • Installing Unicast DNS is easier because you have to be concerned about just one server’s maintenance and decent performance. 
  • It is a perfect option for websites that target specific locations. If your company is focused just on Spanish clients, for example, then you can prefer Unicast DNS. The server is in a particular country, so your website will be simply reachable, considering it is near to your clients.
  • Unicast DNS is cheaper than Anycast DNS.

Unicast DNS disadvantages

  • In case the DNS server that holds the information about your website is under attack or just fails, the access to your website is going to be severely affected.
  • In case your company potentially targets people worldwide, Unicast DNS is not a good choice for you. You are not able to ensure the best experience for your clients who are in a different location other than your server’s area.

If you want more detailed information check the following article: Unicast DNS explained.

Anycast DNS vs. Unicast DNS 

  • In Anycast DNS routing, DNS resolvers are set with an individual Anycast address for each combination of name servers. For that reason, the latency is eliminated. The timeout delays when a resolver has to query a non-responsive nameserver do not happen. Anycast DNS routing automatically excludes unreachable points of presence (PoPs). With Anycast, the DNS resolver is always routed to the closest and best-performing DNS server.
  • In Unicast DNS routing, the DNS resolver, which is accountable for getting the authoritative DNS record for the requested hostname, can concern a large number of DNS name servers. It will ask the first one on the list, pause till it answers, or there is a timeout, and then it will be able to ask the next. So, it is very likely to create high latency.

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