What metrics prove L4 vs L7 Load Balancing is healthy in prod?

Answers use simple, clear English.

Quick interview answer

Prove L4 vs L7 Load Balancing is healthy with latency (p50/p95/p99), error/saturation rates, and queue/event-loop lag — not just CPU. Context: Baseline: L4 (TCP) routes by IP/port fast. L7 (HTTP) routes by path/header/cookie — enables sticky sessions, TLS, WAF integration.

Detailed answer

Production health signals for L4 vs L7 Load Balancing: • Latency: p50/p95/p99 of the critical path that uses L4 vs L7 Load Balancing. • Errors: failure rate, timeouts, and retry storms. • Saturation: queue depth, event-loop delay, thread/pool utilization. • Business SLIs: request success and user-visible freshness where relevant. Trade-off lens: Pros: L7 smart routing; L4 performance for non-HTTP. Cons: L7 terminates TLS — cert management; L4 no URL awareness. Explain thresholds + alerts, then how you triage. Parent context: Baseline: L4 (TCP) routes by IP/port fast. L7 (HTTP) routes by path/header/cookie — enables sticky sessions, TLS, WAF integration.

Full explanation

Good answers name measurable signals and what “bad” looks like for L4 vs L7 Load Balancing. L4 (TCP) routes by IP/port fast. L7 (HTTP) routes by path/header/cookie — enables sticky sessions, TLS, WAF integration.

Follow-up questions

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Parent context — L4 vs L7 Load Balancing

Baseline: L4 (TCP) routes by IP/port fast. L7 (HTTP) routes by path/header/cookie — enables sticky sessions, TLS, WAF integration.

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