What Is Load Balancing?

Key takeaways

• Load balancing distributes incoming network traffic across a pool of backend servers to keep individual servers from becoming overwhelmed.

• Load balancing solutions provide organizations with flexible options to adjust server usage based on customer demand for information access.

• Network load balancing can handle millions of requests per second, making it well-suited for high-traffic applications.

Two types of load balancers include classic load balancers and network load balancers. Discover more about load balancing, including what it is, what load balancers do, and types of load balancing algorithms. If you’re ready to begin developing your skills in this field, enroll in the Google IT Support Professional Certificate. In as little as three months, you’ll have the opportunity to learn about network administration, version control, IT security architecture, computer networking, network troubleshooting, and more. Upon completion, you’ll earn a shareable certificate for your resume.

What is load balancing?

Load balancing is the act of distributing incoming network traffic across backend servers to balance the amount of traffic across a pool of servers. It allows applications to perform better by sending requests to multiple servers, decreasing the burden of managing and maintaining network sessions.

Load balancing allows applications to be readily available to users, boosting performance while also allowing for an extra layer of security for the network.

Read more: Information Technology (IT) Terms: A to Z Glossary

What do load balancers do?

Load balancing relies on dedicated servers used to distribute incoming traffic. The balancer sends requests to servers with the least amount of traffic, requests, or volume of data being distributed.

Sending traffic in different directions allows servers to reliably and efficiently respond to requests from users. It also gives companies flexible options to adjust server use depending on the level of demand for requests from customers trying to access the information.

What are the 4 types of load balancers?

Although other types exist, such as hardware load balancers, take a closer look at these four types of load balancers that can distribute requests evenly across servers in order to avoid overloading one of them. These four types of load balancers are:

Classic load balancer (CLB): Effective for simple load balancing tasks.

Application load balancer (ALB): Works well for load balancing HTTP and HTTPS traffic.

Network load balancer (NLB): Best used when dealing with millions of requests per second.

Gateway load balancer (GLB): Assists in the deployment, scaling, and management of virtual appliances such as intrusion detection systems and firewalls.

Network load balancing: Types of algorithms

You can use different algorithms to help you operate load balancing on a network, depending on your needs. The list below shows some common algorithms you can utilize.

• Round robin: The load balancer delivers requests equally throughout the group of servers. The load balancer sends traffic to servers based on a preset order, so each server takes on an equal amount of traffic. This option works best when you expect clients to make requests that are similar, so that it doesn’t overwhelm one server while underutilizing another.

• Least connections: The load balancer sends traffic to the server with the fewest current connections. Use this option if you’re not sure how long a client’s connection with the server will last, prioritizing servers with open connections while other servers may still be handling client traffic.

• IP hash: The load balancer uses a client’s IP address to determine where to send traffic. This version of load balancing works if you have an organization that deals with multiple international clients.

• Random: A server at random handles the requests of clients based on an algorithm. You can also choose the random "power of two choices" algorithm, in which the load balancer picks two servers randomly and then chooses the best to handle the client’s traffic.

Related terms

• Computer networking

• Server maintenance

• IT support

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