What is DNS Cluster? The Structure and the Benefits

Posted on November 29th, 2016


DNS stands for domain name system and it resolves domain names to IP addresses. Since domain names are alphabetic, they’re easier to remember by users. The internet works based upon IP addresses. When we use a domain name, therefore, a DNS service must translate the domain name into the corresponding IP address. For example, if we search the domain www.example.com in our browser it might translate to its corresponding IP address. The DNS system has its own network. If one DNS server doesn’t know how to translate a domain name, it asks another nameserver, and so on, until the correct IP address is returned.



DNS cluster is a service and it has a group of name servers that share records with each other. It allows physically separate nameservers that handle the domain name requests from web servers. In the event of, a power outage, currently you still have DNS functionality. In this way, visitors can easily get websites on your server more quickly after the web server comes back online. DNS resolves domain names to an IP address. This is one step in loading a website. In this type of instances DNS cluster will give a backup for name resolution.


Benefits of DNS cluster

1) 0% downtime when DNS service is down. If the DNS service is down the domain DNS will be served by the other server in the cluster.

2) When the server  is down someone will send an email to a domain on that server. They  will recieve a delivery failure error. In the case of a DNS cluster setup, there will be no delivery failure report message sent

3) We can use Global nameservers for all your servers. Here we do not need to set specific nameservers for each other.


Cluster Structures

1) Use direct links

To improve the performance of our servers, link web servers directly to the DNS servers. In this case webserver.example.com sends domain name system information directly to ns1.example.com and ns2.example.com


2) Use the primary nameserver as an intermediary

In this case the primary nameserver is placed between the web server and the secondary server. For each server that we add, data will transfer two times slower than the direct link. To create this configuration, set the webserver.example.com (web server) to sync towards primary name server. Then set the primary name server to synchronize data to the secondary (ns2.example.com) nameserver.


3) Use multiple intermediary nameservers

Multiple intermediary nameservers uses multiple steps between the web server and nameservers. If we configure multiple steps between a web server and nameserver, the server’s performance will be slower. In this example for web server (web1.example.com) to communicate with ns2.example.com, this time the information must pass through two intermediary servers. This increases the load on the servers, because the DNS software updates the nameserver information on each step. This will take more memory from the server and it’s configuration slows the server’s response time remarkably.


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