Follow-up · depth 4
What are common failure modes of L4 vs L7 Load Balancing?
What are common failure modes of L4 vs L7 Load Balancing?
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Audio N/AQuick interview answer
Common failures around L4 vs L7 Load Balancing: blocking the hot path, ignoring backpressure, and weak timeout/retry design. L7 LB without health checks; single LB bottleneck.
Detailed answer
Failure modes for L4 vs L7 Load Balancing: Known pitfalls: L7 LB without health checks; single LB bottleneck. • Missing timeouts / unbounded retries • No backpressure when downstream slows • Assuming ordering/guarantees the runtime does not provide How seniors prevent them: Health check app endpoint not TCP only; cross-zone LB. Parent context: 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..
Full explanation
Name concrete failure modes and the mitigation for each — that scores higher than a vague “it can fail.” 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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