How do you make ALB highly available across AZ failures?

Summary

Make ALB highly available by designing across multiple Availability Zones and removing single-AZ stateful dependencies.

Longer Answer

For ALB, the service-specific pattern is enable at least two AZs, keep healthy targets in each AZ, use target group health checks, and avoid single-AZ backend dependencies. Multi-AZ is not just a checkbox; traffic routing, health checks, capacity, data stores, and network egress must all survive an AZ impairment.

A good answer includes a failure test: disable or drain one AZ path in a non-production environment and verify users see no meaningful outage.

Key Points

• For ALB, the service-specific pattern is enable at least two AZs, keep healthy targets in each AZ, use target group health checks, and avoid single-AZ backend dependencies
• Multi-AZ is not just a checkbox; traffic routing, health checks, capacity, data stores, and network egress must all survive an AZ impairment
• A good answer includes a failure test: disable or drain one AZ path in a non-production environment and verify users see no meaningful outage
• For 'How do you make ALB highly available across AZ failures?', interviewers are looking for a decision process: state the requirement, name the AWS mechanism, describe the limit or failure mode, and explain how you would verify it in production. A good answer includes a failure test: disable or drain one AZ path in a non-production environment and verify users see no meaningful outage.

Use the comparison table to show that you understand tradeoffs rather than memorizing a single preferred service

Comparison / Tradeoffs

Use the comparison table to show that you understand tradeoffs rather than memorizing a single preferred service. |

Summary

Make ALB highly available by designing across multiple Availability Zones and removing single-AZ stateful dependencies.

Longer Answer

For 'How do you make ALB highly available across AZ failures?', interviewers are looking for a decision process: state the requirement, name the AWS mechanism, describe the limit or failure mode, and explain how you would verify it in production. A good answer includes a failure test: disable or drain one AZ path in a non-production environment and verify users see no meaningful outage.

Use the comparison table to show that you understand tradeoffs rather than memorizing a single preferred service.

Key Points

• For 'How do you make ALB highly available across AZ failures?', interviewers are looking for a decision process: state the requirement, name the AWS mechanism, describe the limit or failure mode, and explain how you would verify it in production
• A good answer includes a failure test: disable or drain one AZ path in a non-production environment and verify users see no meaningful outage
• Use the comparison table to show that you understand tradeoffs rather than memorizing a single preferred service
• Use the answer to connect the concept back to a realistic production or interview scenario for 'How do you make ALB highly available across AZ failures?'

Comparison / Tradeoffs