How would you explain L4 vs L7 Load Balancing to a junior engineer?

Answers use simple, clear English.

Quick interview answer

Explain L4 vs L7 Load Balancing in one sentence, then a tiny example, then one “don’t do this” tip. Use L4 vs L7 Load Balancing as the core idea. Example shape: ALB routes /api → API target group, /static → S3; NLB for gRPC TCP passthrough..

Detailed answer

Junior-friendly explanation of L4 vs L7 Load Balancing: Plain English: Use L4 vs L7 Load Balancing as the core idea. Example shape: ALB routes /api → API target group, /static → S3; NLB for gRPC TCP passthrough.. Tiny example: ALB routes /api → API target group, /static → S3; NLB for gRPC TCP passthrough. One warning: L7 LB without health checks; single LB bottleneck.

Full explanation

Keep jargon low, then layer detail. 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

Use L4 vs L7 Load Balancing as the core idea. Example shape: ALB routes /api → API target group, /static → S3; NLB for gRPC TCP passthrough..

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