DNS Round Robin vs Load Balancing – What’s the Difference ?

DNS Round Robin vs Load Balancing – What’s the Difference? Modern websites and applications serve millions of users fast and efficiently. Altogether, they deliver videos, images, data, and text. Because, in order to operate so seamlessly, organizations spread the workload across several servers. This way, the risk of slowdowns, dropped requests and server crashes reduces. More importantly, servers aren’t overworked. And this is where load balancing and DNS Round Robin come in. 

Generally, DNS round robin and load balancing are two sides of the same coin. As a result, they’re a bit hard to distinguish. Hence, this article assists in explaining the difference between DNS Round Robin and Load Balancing. On balance, you also learn how you to use them to optimize the operations of your website or application.

Shall we start with DNS Round Robin vs Load Balancing – What’s the Difference? 

What is DNS Round Robin?

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First of all, DNS Round Robin is a load balancing technique that helps manage DNS responses to address requests. Instead of using a piece of hardware, the load balancer is a type of DNS server referred to as an authoritative nameserver. 

So, when should you use DNS Round Robin? Hence, this load balancing method comes in handy when you have a service or website with content hosted on several redundant web servers that are geographically separated. Implementing traditional load balancing in such a setup is difficult.

How Does DNS Round Robin Work?

In DNS Round Robin load balancing, two or more IP addresses are assigned to the same DNS record. Traffic is then equally dispersed across all IP addresses. Whenever the DNS authoritative nameserver receives an IP address request, the server gives out a different address each time following a sequence. Besides, it essentially works on a rotation basis where IP addresses of servers are given out one after the other until the end of the list in a looping fashion.

In order to illustrate, IP addresses in a DNS Round Robin setup are like baseball players in a batting lineup. Every player (IP address) gets a turn and then moves to the back of the line. Here’s an example of a DNS Round Robin configuration:

Host Redirects to:

In the example above , the first user to access the website roundrobinserver.com is directed to ip.1.server. Well, the second user accessing the website is directed to ip.2.server.  When the third user submits a request, they’re directed to ip.3.server. After ip.3 sever, the next user is directed back to the first server (ip.1.server), and so on.

Advantages of DNS Round Robin

  • Implementation of DNS Round Robin is easy and affordable. 
  • Helps with DNS traffic management by reducing stress at specific points of the network.
  • Improves the speed and performance of the network

Disadvantages of DNS Round Robin

  • DNS round robin doesn’t check whether a server is down before sending traffic. So users may keep getting redirected to an inactive server. 
  • It disregards server load, transaction time, and network load when rotating IP addresses. As a result, the network may not perform optimally. 
  • DNS round robin does not consider server resources such as CPU and RAM, so lower capacity servers often get overloaded. 
  • A public IP address is needed for each server. 

What is Load Balancing?

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Second tool we discussing is a concept of load balancing. Though, a distribution of network traffic across a pool of servers. In that case, it improves the availability of network service by spreading workloads across multiple servers. Examples of scenarios where load balancers come in handy include application severs, database servers, web servers, and other network services.

In summary, a load balancer helps you achieve the following:

  • Distributes user requests efficiently across multiple servers with duplicate data. 
  • Ensures high reliability and availability of services by sending traffic to available servers. 
  • Adds or removes servers seamlessly as demand for services fluctuates.

How Does Load Balancing Work?

To clarify, a load balancer sits between the users and servers. Acts as a “traffic cop” that directs user requests to different servers. In turn, it optimizes speed and capacity utilization during the fulfilment of client requests. Result is, no server gets overloaded. Should a server go down, the load balancer redirects and distributes requests to the remaining servers. Accordingly, there’s a reduction in downtimes. 

Here’s an example to illustrate how a load balancer works.

Step 1: A user submits a request via a browser or application. 
Step 2: The load balancer receives the request and redirects it to a server in the group of servers available
Step 3: Next, the target server gets the connection request and responds to the browser or application via the load balancer
Step 4: The load balancer matches the IP of the application/browser with the IP of the selected server. Next, it forwards the packet with the response to the request the user had submitted. 
Step 5: In some instances, the load balancer also handles date decryption using Security Socket Layer (SSL) protocol, so the servers don’t have to do it
Step 6: This process iterates until the session is complete. 

Types of Load Balancers

Certainly, a load balancer is either physical (hardware) or virtual (software): 

  • Hardware load balancers are physical appliances that direct traffic to a pool of servers. They redirect traffic based on server performance, processor utilization, and active connections to the server. Unfortunately, hardware load balancer vendors pre-load proprietary software into the machines they provide. As a result, you need to buy more or bigger appliances from the vendor to deal with increasing traffic to your application or website. 
  • Software load balancers are often easier to deploy than their hardware counterparts. They’re flexible, cost effective and available as installable solutions or cloud service (SaaS) platforms. Note that installable software load balancers often need configuration. 

Advantages of Load Balancing

  • Improves the user experience for end users by lessening the load on a server.
  • Replaces defective or underperforming servers without causing downtimes.
  • Predicts traffic bottlenecks before they happen.
  • Acts as an extra layer of security for websites and applications.
  • Allows for scaling of server infrastructure on demand without impacting services.

Disadvantages of Load Balancing​

  • There is need to perform additional configuration to maintain connections between servers and clients. Also, you need to reconfigure the load balancer any time there’s a change in the downstream cluster topology. 
  • Hardware load balancing is usually expensive. 

DNS Round Robin vs Load Balancing - The Differences

As mentioned earlier, DNS Round Robin is a load balancing technique that differs from standard load balancing techniques in several ways. Here’s a breakdown of the differences:

Differences Between DNS Round Robin and Load Balancing: Weight Distribution

The most obvious difference between basic Round Robin and other load balancing methods is how weight is distributed. Whereas, Round Robin requires an equal distribution, other load balancing techniques allow you to set values unequally. As a result, you get more efficient distribution of network resources. In short, DNS Round Robin is a basic form of load distribution while Load Balancing is a more advanced technique of load distribution. 

Difference between DNS Round Robin and Hardware Load Balancing

A hardware load balancer relies on a physical appliance that distributes web traffic across multiple network servers. DNS Round Robin uses a DNS server that redistributes traffic to several redundant web servers.

Difference Between DNS Round Robin and Weighted Load Balancing

Primary difference here, DNS Round Robin assumes that all servers are equal and handle equivalent loads. But the reality is different. Most setups have servers with different CPU, RAM, and storage capacities. Unfortunately, DNS Round Robin has no way to distribute jobs based on server capacity. As a result, some servers may fail to overload as others lie idle.
With weighted load balancing, site admins assign weights to servers based on their load handling capacity. As a result, servers with higher capacity get the bulk of the jobs.

Difference Between DNS Round Robin and Network Load Balancing

Moreover, DNS Round Robin relies on the DNS server to distribute traffic sequentially to all the available servers. It doesn’t take into account the capacity or availability of the servers. NLB is a more advanced load balancing method. It relies on protocols and algorithms to distribute traffic. While at it, NLB considers the current server load, server capacity, and client’s location.

Difference Between DNS Round Robin and Least Connections Load Balancing

Least connection load balancing minimizes the chances of server overload by sending requests to the server with the least active connections at any one time. For DNS round robin, requests are sent sequentially from one server to the next without considering the number of active connections.

Other Differences Between DNS Round Robin and Load Balancing

1.You can hide server IP addresses and port numbers with other load balancers, but it’s impossible with DNS Round Robin. 

2. With DNS Round Robin, DDOS attacks affect the host servers directly. With other load balancing methods, ddos attacks only affect the load balancer IP. 

3. It’s impossible to match requests to the geographical region of origin when using DNS Round Robin. More sophisticated load balancers can do this. 

4. A load balancer is usually a single point of failure. DNS Round Robin doesn’t suffer this shortcoming because DNS records are hierarchically updated worldwide and cached in local DNS. As a result, IP resolution is faster. 

5. Load balancing uses a single TCP connection for multiple HTTP requests, hence reducing congestion. This is not applicable in the DNS Round Robin. 

This is it! Thank you for reading DNS round Robin vs load balancing – what’s the difference? Now to conclude.

DNS Round Robin vs Load Balancing – What’s the Difference? Conclusion

Finally, load balancing and DNS Round Robin are two different methods of distributing traffic to a pool of servers in a network. However, load balancing refers to a general category of traffic management technologies and techniques. Load balancing techniques include software load balancers, cloud based load balancers, and hardware load balancers.

Concluding, DNS Round Robin is a specific load balancing method that relies on the DNS server to distribute traffic to servers in the network. Concurrently, it’s a simple and cost effective load balancing method since it doesn’t require special software or hardware. However, it treats all servers equally without considering the load and current capacity of the servers while distributing traffic. Consequently, DNS Round Robin leads to performance issues.

While DNS round robin has its flaws, it’s still one of the most popular load balancing methods available. If you find it too simplistic for your needs, you opt for weighted round robin or dynamic round robin, both of which take into account the criteria ignored by DNS round robin. 

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Avatar for Richard Kanyoro
Richard Kanyoro

The world’s biggest problems can be solved by progressively solving the little ones. I write to help people solve the “little” tech problems they face.

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