What does a load balancer do?

What a load balancer does?

A load balancer intelligently distributes traffic from clients across multiple servers without the clients having to understand how many servers are in use or how they are configured. Because the load balancer sits between the clients and the servers it can enhance the user experience by providing additional security, performance, resilience and simplify scaling your website.

Clients connect to a single URL (e.g. www.example.com) and the load balancer will secure the connection and decide which of the servers is best able to service the client (least busy, least number of connections, best response time etc.).

The Benefits of a Load Balancer

1. Security

A load balancer can add additional layers of security to your website without any changes to your application.

Protect applications from emerging threats
The Web Application Firewall (WAF) in the load balancer protects your website from hackers and includes daily rule updates just like a virus scanner

Authenticate User Access
The load balancer can request a username and password before granting access to your website to protect against unauthorized access

Protect against DDoS attack
The load balancer can detect and drop distributed denial-of-service (DDoS) traffic before it gets to your website

Simplify PCI compliance
If you process credit cards, you need to comply with Payment Card Industry (PCI) regulations. A load balancer simplifies compliance with PCI rules

2. Performance

Load balancers can reduce the load on your web servers and optimize traffic for a better user experience.

SSL Offload
Securing traffic with SSL (Secure Sockets Layer) on the load balancer removes the overhead from web servers resulting in more resources being available for your web application

Traffic Compression
A load balancer can compress website traffic giving your users a much better experience with your website

Traffic Caching
A load balancer will retain a copy of frequently accessed elements of your website such as images resulting in fewer to your web servers and quicker delivery of content to users

HTTP 2.0 Support
HTTP 2.0 is an enhancement to the HTTP protocol which results in much quicker websites. A load balancer can communicate with clients using HTTP 2.0 even if not supported by your web servers

3. Resilience

Load balancers can transparently accommodate failed and under-performing components to maintain user service.

Continued service if a web server fails
If one of your web servers fails, the load balancer will continue to transparently provide service to the remaining servers with no impact on the user

Workaround busy servers
If a web server is busy, the load balancer will detect this and redirect traffic to less busy web servers

Create a highly available site
Load balancers can be deployed in highly available pairs so that if one fails, the other load balancer immediately takes over with no impact on users

Simplify business continuity
If you have an application in multiple sites for disaster recovery, a load balancer can detect a site outage and seamlessly redirect users to the alternate site

4. Scalability

A load balancer makes it easy to change the server infrastructure without disrupting service to users.

Simplify business continuity
If you have an application in multiple sites for disaster recovery, a load balancer can detect a site outage and seamlessly redirect users to the alternate site

Easily add additional servers
If you need to add more website capacity, this can be easily done by deploying an additional server on the load balancer and it will transparently be available to users

Cloud auto-scaling
If your website is cloud hosted and needs to adjust to meet varying demand, a load balancer simplifies this process without any client-side changes

Avoid disruptive upgrades
With a load balancer in place, capacity can be easily added with additional servers rather than upgrading and existing server which can be costly and involves downtime