What is DNS Round-Robin?

What is DNS Round-Robin?


DNS round-robin is a technique of distributing load among multiple servers. It’s often used as an alternative to the more common DNS load balancing. The main difference is that DNS load balancing requires at least two different IP addresses for a given hostname or FQDN (Fully Qualified Domain Name), while the round-robin technique only requires one.

DNS round-robin works by assigning IP addresses in sequential order, such that each server gets the same proportion of requests over time. Round-robin DNS can be employed on its own or together with other methods like IP address rotation and geographic location distribution.

What is DNS round robin and how does it work?

DNS round-robin is a method of load balancing IP addresses. It can be used to provide failover and fault tolerance for server farms and other applications that process large amounts of data. DNS round-robin works by assigning one IP address from the pool to service an initial connection request while subsequent requests are assigned different IPs in the pool. The TCP connection will be maintained while the IP address will change which will prevent congestion on any single server.

DNS round-robin works by having a pool of servers that each have their own IP address. When a new connection is started with the first server’s IP, the DNS sends this request to the first server in the list or pool. The server with the assigned single IP address for this round will now serve as the processing point as well as the point for all responses. Once the client requests data from this server, it will remain on that IP until either a reboot or administrative action takes place. The client’s TCP stack remembers the DNS response and requests to connect back to the same server to finish its communication.

How to use DNS round-robin?

DNS round-robin is a setup in which an organization’s web server or application server software is configured to serve incoming requests using multiple Internet Protocol addresses, balancing the load across all the available servers. It is often used in content delivery networks to balance web traffic between data centers.

The DNS round-robin method is helpful when you have more than one website with the same name in your domain. This eliminates any confusion in indexing problems that may arise when Google crawls your site and returns different pages of results based on whether it’s crawling the first site it finds (the default) or others within your domain (based on DNS round-robin). It’s also common for organizations to use this method when they want to share incoming requests across more than one Internet Protocol (IP) address, such as with a server load-balancing cluster.

What are the benefits of using DNS round-robin?

The main benefit of using DNS round-robin is to provide for alternating load distribution among child servers. This works well if you have multiple servers which are able to roughly equalize the workload (e.g., two servers), but it is less effective if you have multiple servers that are not approximately balanced (e.g., three or more).

Another big benefit of round-robin DNS is that it can provide a ‘failsafe’ in the event of failure. In the example below, server 1 fails and server 2 picks up the traffic from all four clients. In this way, even if one of your servers should fail, another may simply take its place and continue servicing requests.

What are the drawbacks of using DNS round-robin?

A drawback of using DNS round-robin is that it will only work if the Web server has several IP addresses. If the Web server only has one IP address, then DNS will not be able to divide the traffic between the servers.

Another drawback is that it does not take into consideration how busy each of the servers is. If one of them is constantly busy and therefore unresponsive, that host will still receive the same amount of requests as a host which isn’t as busy. This means it might be time to consider another DNS solution.


DNS round-robin is a type of load balancing that relies on the DNS to direct traffic to multiple servers in turn. It can be used for high availability and performance, but it has its drawbacks as well: If one server fails, all requests will fail because there’s no backup option available. The best way to use this tool would be when you have two or more servers with equal capacity running at 100% uptime so they’re ready when needed without any downtime. In addition, if your service requires quick response times such as email services then using round-robin may not work well since the time between requests could vary greatly which causes delays in receiving responses from other mailboxes. Round Robin works better with slower-paced services like file sharing where there is no need to respond quickly.

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