What is loadbalancer?
A load balancer is a device or software that sits between users and a group of servers, directing incoming traffic so that no single server gets overwhelmed. It spreads the work evenly, making sure each request is handled by the healthiest and least busy server.
Let's break it down
- User request: Someone on the internet clicks a link or sends data.
- Load balancer: Receives that request first.
- Decision logic: Checks which server is most available or meets certain rules.
- Server pool: A collection of identical servers ready to handle requests.
- Forwarding: The load balancer sends the request to the chosen server, then returns the response to the user.
Why does it matter?
- Reliability: If one server fails, the load balancer redirects traffic to the others, keeping the service up.
- Performance: By sharing the load, each server works faster, reducing wait times for users.
- Scalability: Adding more servers is easy; the load balancer automatically includes them in its pool.
Where is it used?
- Websites with high traffic (e.g., e‑commerce, news sites)
- Cloud services and APIs
- Online gaming servers
- Corporate applications behind firewalls
- Any system that needs to handle many simultaneous connections reliably
Good things about it
- Improves uptime and reduces single points of failure
- Enhances user experience with faster response times
- Allows seamless scaling by adding or removing servers
- Can perform health checks to ensure only healthy servers receive traffic
- Supports different routing methods (round‑robin, least connections, IP hash, etc.)
Not-so-good things
- Adds an extra layer of complexity to the architecture
- Can become a bottleneck or single point of failure if not redundant
- Requires proper configuration; misconfiguration may lead to uneven load or downtime
- May introduce slight latency due to the extra hop
- Some advanced features (SSL termination, session persistence) may need additional licensing or resources.