How would you debug production issues related to AWS VPC, Subnets, and Security Groups?

Answers use simple, clear English.

Quick interview answer

Debug AWS VPC, Subnets, and Security Groups by confirming blast radius, checking lag/error metrics, grabbing profiles/traces, then mitigating before deep root-cause. VPC CIDR, public/private subnets, IGW/NAT, route tables. Security groups stateful allow-lists; NACLs stateless.

Detailed answer

Production debug playbook for AWS VPC, Subnets, and Security Groups: 1) Stabilize: rate-limit, shed load, or roll back if users are hurting. 2) Orient: dashboards for latency, errors, saturation tied to AWS VPC, Subnets, and Security Groups. 3) Evidence: traces, profiles, logs with correlation IDs. 4) Hypothesize + prove with a safe experiment. 5) Fix + add a regression test/alert so it cannot silently return. Watch for: 0.0.0.0/0 on SSH SG; databases in public subnets. Parent context: VPC CIDR, public/private subnets, IGW/NAT, route tables. Security groups stateful allow-lists; NACLs stateless.

Full explanation

Interviewers score structured incident thinking: mitigate → measure → root cause → prevent. VPC CIDR, public/private subnets, IGW/NAT, route tables. Security groups stateful allow-lists; NACLs stateless. Private workloads without public IPs.

Follow-up questions

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Parent context — AWS VPC, Subnets, and Security Groups

VPC CIDR, public/private subnets, IGW/NAT, route tables. Security groups stateful allow-lists; NACLs stateless.

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