juniorLoad Balancing
What is Layer 4 (L4) Load Balancing?
Updated Apr 28, 2026
Short answer
Load balancing based on network layer protocols like IP address and TCP/UDP ports without inspecting the packet content.
Deep explanation
Load balancing is critical for horizontal scaling. By sitting in front of a server farm, it ensures no single server becomes a bottleneck. It also provides high availability; if one server fails, the LB stops sending traffic to it until it recovers.
Real-world example
A small website using Nginx to split traffic between two identical web servers.
Common mistakes
- Forgetting to configure health checks, causing the LB to send traffic to crashed servers.
Follow-up questions
- What is a reverse proxy?