Load Balancing Algorithms: How They Work Under the Hood

Round Robin

Sequential rotation. O(1) per request. No state needed.

Weighted Round Robin

Weighted random selection. Probabilistic distribution over time.

IP Hash

Deterministic hash of client IP. Consistent mapping.

Least Connections

Route to server with fewest active connections. Requires state tracking.

Trade-offs

Algorithm

Complexity

State

Fairness

|-----------|-----------|-------|----------|

Round Robin	O(1)	None	Equal
Weighted	O(1)	None	Proportional
IP Hash	O(1)	None	Consistent
Least Conn	O(n)	Required	Optimal