What is Network Load Balancing? Understanding Traffic Distribution

As a business, one of the best-case scenarios is that users adopt your application, visit your website, or purchase your products in more significant numbers than anticipated. But sometimes you can grow faster than expected, facing an unexpected surge in traffic or demand. A viral TikTok might send your app from a couple hundred users to thousands overnight. Your Black Friday e-commerce sale might generate ten times more sessions per minute than you originally planned. The launch of a much-requested feature might bring back dormant users while attracting new ones, creating a perfect storm of activity on your servers.

What should be a moment of celebration can quickly turn into a crisis if your infrastructure buckles under the pressure. Customer experience suffers as pages load slowly, transactions time out, or worse—your service becomes completely unavailable. Network load balancing helps businesses handle these fluctuations by distributing traffic across multiple servers, automatically scaling resources up during peak times and down during quieter periods. This ensures consistent performance and reliability even when facing unexpected surges in demand.

Read on to learn more about network load balancing, its benefits, and how it can serve as a security blanket for unexpected growth, protecting both your customer experience and your business reputation during critical moments.

What is network load balancing?

Network load balancing (NLB) is the process of distributing network traffic across multiple servers to ensure no single server becomes overwhelmed, improving application availability and performance. It works by receiving incoming requests and routing them to the most appropriate server based on factors such as current load, server health, and configured distribution algorithms.

This is similar to traffic police standing on a busy street to regulate the traffic flow for a better experience for all, avoiding any congestion on the road. It also helps to optimize the performance of your website or application, offering users a better experience and reducing the risks of server crashes and downtime.

How does cloud-based load balancing work?

Cloud-based load balancing is provided as a service by cloud providers (like DigitalOcean, AWS, Google Cloud) where the load balancing infrastructure is hosted, managed, and maintained by the provider. You configure the service through a control panel or API, and the provider handles the underlying hardware, software updates, and scaling.

On-premises load balancing, on the other hand, involves deploying and managing physical or virtual load-balancing appliances within your own data center or infrastructure. This approach gives you more direct control over the hardware and configuration but requires you to handle maintenance, updates, and scaling yourself. Here’s more on how each differs:

Many organizations use a hybrid approach, implementing both models depending on where their applications are hosted and their specific requirements for control, cloud compliance, and cloud cost management.

Components of network load balancing

Effective network load balancing relies on the interaction of three main components:

Load balancers

Load balancers are the primary point of contact for incoming traffic and redirect the traffic to the available servers based on the load balancing algorithms and health checks for individual servers. This helps to ensure that the traffic is being redirected to a suitable server and the server is not overloaded.

Listeners

Listeners are components that check for and monitor incoming network traffic on specific protocols and ports. They essentially act as the “ears” of a load balancer, waiting for and identifying connection requests. These are designed to recognize any specific request such as HTTP, HTTPS, or TCP traffic.

Depending on the information that is gathered by the listeners, they direct the user request and the incoming traffic to a dedicated server suitable for the specific request. You can also add multiple listeners to streamline the process and increase the flexibility of the load balancers.

Target groups

Lastly, we have target groups. These are collections of backend resources (servers, instances, or containers) that receive traffic distributed by the load balancer. They represent the destinations where your actual application or service is running. For example, you might have one target group for your web servers, another for your application servers, and a third for your API servers. The load balancer uses listeners to identify traffic types and then routes that traffic to the appropriate target group based on the rules you’ve defined.

Benefits of network load balancing

Organizations of all sizes—from startups to enterprise-level corporations—rely on load balancing to ensure their applications remain available, responsive, and resilient under varying traffic conditions. Some of the major benefits of integrating server load balancing into your business include:

• Better performance. With an NLB process in place, your applications can perform better and offer your users quick responses.

• Increased availability. With application load balancing, servers avoid overload and are capable of better handling the incoming traffic. This helps to increase the availability of your servers for better results.

• Server optimization. Distributing incoming traffic across multiple servers prevents any single server from becoming overwhelmed, ensuring each server operates within its optimal capacity range.

• Scalability. With growing demand, you can scale your business by adding more servers to existing servers.

Different types of load balancing

Load balancing solutions come in several varieties, each designed to address specific technical requirements. The right choice depends on factors like your application architecture, expected traffic patterns, and the level of content inspection needed for optimal routing decisions. For example, media streaming platforms typically benefit from Layer 4 load balancing’s raw speed and simplicity, while e-commerce sites often require Layer 7’s sophisticated content inspection to route customers to the correct product servers based on their browsing history or shopping cart contents. Here are some of the most common types of load balancing:

Layer 4 load balancing

Also known as transport layer load balancing and is a quick way of transporting or distributing the incoming traffic to different servers based on the IP addresses or port numbers.

It assigns traffic requests without assessing the traffic packet and makes the entire process quick and convenient. It is a suitable strategy for platforms where only performance matters and high responsiveness is required such as streaming videos.

This approach is ideal for startups that require simplified processing along with speed.

Layer 7 load balancing

This is also known as application load balancing and inspects the contents of the traffic requests before assigning them to different servers. It enables advanced features such as SSL termination and others to ensure the user’s requests are redirected to the correct server.

This type of load balancing is best for organizations where the processes are a bit complex and results are required on a personalized end such as based on the user history and behavior, like e-commerce platforms.

DNS-based load balancing

With DNS or the Domain Name System-based load balancing, a traffic request is received for a domain name, the DNS server offers different IP addresses using different strategies such as round-robin to offer the result.

This is a simple process and doesn’t require any specific hardware to be integrated for processing. Businesses that are widely spread out with services in a large geographical area with simple traffic distribution needs can integrate DNS-based load balancing.

Also, any small-medium scale business with limited IT resources can look into this form of load balancing.

What are the different types of load-balancing algorithms?

Load balancing algorithms determine exactly how traffic is distributed across your server pool, directly impacting application performance and resource utilization. Each algorithm offers a unique approach to traffic distribution based on different priorities: Below are some of the most commonly used load-balancing algorithms:

Round Robin

In this algorithm, the traffic distribution is sequential which helps to create a balance between all the servers. This algorithm is recommended if all your servers have similar capacity, as the sequential distribution of the incoming traffic will be evenly distributed.

Least connections

With this approach, the incoming or new traffic and user requests are redirected to the servers with the least amount of active connections. This might be a bit slow process but is ideal for applications and services where the response time is a bit delayed as compared to others. One of the best examples of this is the difference in the size of file downloads.

Dynamic

In this algorithm, the servers adjust based on real-time data such as the server load, or response time to identify the most suitable server for the upcoming traffic requests. This is an ideal algorithm to be used for businesses with fluctuating demand.

Weighted

This algorithm consists of two different subcategories—weighted round robin, and weighted least connections. Each server is assigned a weight based on its capacity. Based on this weight or capacity the incoming traffic requests are redirected from the higher capacity to lower capacity servers.

Network load balancing use cases

When traffic surges, your system’s resilience is only as strong as its ability to distribute the load. Network load balancing works behind the scenes in numerous scenarios to prevent crashes, maintain uptime, and deliver consistent performance when demand spikes.

E-commerce platforms during flash sales

Flash sales, such as Black Friday or limited-release product launches, create intense spikes in web traffic as customers simultaneously rush to secure deals or exclusive items. This rapid influx of concurrent shoppers overloads web servers, causing slow-loading pages, failed checkouts, or site downtime.

Network load balancing addresses this by evenly distributing customer sessions across multiple servers, preventing individual servers from becoming overwhelmed. This ensures stable shopping carts, smooth transactions, and reliable page performance, even at peak moments.

SaaS apps experiencing viral adoption

SaaS applications can experience sudden, intense user growth when featured on social media platforms like Reddit, Product Hunt, or Hacker News. This viral exposure drives a massive influx of new registrations, simultaneous logins, and extensive feature interactions within a short timeframe. This unexpected traffic surge strains the application’s infrastructure, degrading performance, slowing API responses, and interrupting user authentication.

Network load balancers dynamically allocate incoming user requests among multiple backend servers, handling increased database queries and processing demands.

Media sites managing trending content traffic

Media sites attract significantly increased visitor traffic during breaking news events, major sporting events, or unexpected global incidents, as audiences immediately seek real-time updates. Sudden demand for news articles, live video streams, or multimedia content can rapidly exhaust bandwidth and overload individual servers. Without effective load management, websites experience slow page rendering, video buffering, or complete downtime precisely when user engagement is highest.

Network load balancing evenly distributes visitor traffic across multiple servers and content delivery networks, ensuring consistent content availability and rapid loading speeds.

What is Network Load Balancing FAQs

What is network load balancing, and why is it important?

Network load balancing distributes traffic across multiple servers to improve reliability, and performance, and prevent server overload. It helps to evenly distribute the incoming traffic on the servers to offer your users a better experience.

How does a load balancer distribute network traffic?

A load balancer uses different algorithms such as round robin, weighted, dynamic, and least connections to evenly distribute the traffic among all the servers.

What is the difference between Layer 4 and Layer 7 load balancing?

Layer 4 load balancing is quick and doesn’t assess the contents of the traffic request. This is ideal for businesses where speed is required. Layer 7 load balancing is a more complex process, as it assesses the contents of the traffic request, and the servers are assigned based on these contents. It helps to assign a better-suited server to the traffic requests.

What are the different types of load-balancing algorithms?

The different types of load balancing algorithms include round robin, weighted round robin, weighted least connections, least connections, and dynamic.

How does cloud-based load balancing work?

Cloud-load balancing leverages cloud infrastructure and APIs for automatically distributing the traffic across different servers.

How do I choose between a hardware and software load balancer?

To choose between a hardware and software load balancer you need to consider your budget, business needs, and the technical requirements for both the load balancers. If you are a small-medium scale enterprise integrating software load balancers is a great choice as these are cost-efficient while offering you high performance. Whereas for a large-scale enterprise requiring high-traffic load management, having a dedicated hardware load balancer is the best choice.

Can network load balancing improve security?

Yes, network load balancing can help to improve security by protecting your server with features like DDoS protection and SSL management.

References

• How to choose a data center location for your business

• An Introduction to HAProxy and Load Balancing Concepts

• Transmission Control Protocol

• What is DNS-based load balancing?

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