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Design a multi-region active-active deployment

PremiumCloud infrastructureHard

  • Active active
  • Multi region replication
  • Conflict resolution

Quick answer

This cloud infrastructure interview question asks you to design a multi-region active-active deployment. Aim for a design that runs reliably and securely in the cloud at a sensible cost, then explain the services, regions, deployment and trade-offs. Interviewers want to see how you balance reliability, security and cost.

The problem

Design a multi-region active-active deployment for a global shopping app: three regions serve users at the same time, and any two can carry the third's users if it fails. The hard parts are writes to the same data in two regions, keeping enough spare capacity, and failing over without split-brain or double charges.

The app has a product catalog, carts, user profiles, orders and payments. Today it runs in one region with a cold standby. The new design runs in US, EU and Asia-Pacific regions.

What must a multi-region active-active deployment do?

  • Serve locally: Route each user to the nearest healthy region; reads and most writes finish in that region.
  • Region failover: When a region fails, move its traffic to the other two within 5 minutes, automatically or with one command.
5 more requirementsUnlock to see all

How well must it do it?

  • Latency: p99 under 200 ms for API calls on each continent.
  • Availability: 99.99% for the service; losing one region has no visible impact beyond the failover window.
3 more requirementsUnlock to see all

What scale should you design for?

Use these numbers in your estimates.

The scale numbers unlock with this questionUnlock

Key concepts

  • Active active
  • Multi region replication
  • Conflict resolution
  • Global load balancing
  • Regional failover
  • Capacity headroom

How you’ll practise

6 short steps · save and come back any time
  1. Requirements
  2. Environments and topology
  3. Deployment pipeline
  4. Reliability and disaster recovery
  5. Observability and cost
  6. Wrap-up

Lala, personalized to you, gives a hint when you ask and reviews your design when you are ready.

What do interviewers look for?

In any cloud infrastructure design round.

  • Clarifies availability, security and cost targets
  • Chooses managed services with reasons
  • Plans regions, zones and failover
  • Covers identity, secrets and network boundaries
  • Explains deployment, rollback and observability
  • Keeps an eye on cost as usage grows

Questions people ask about this interview question

Which design type is this question?
It is a cloud infrastructure question. You design a multi-region active-active deployment and explain your choices the way you would in an interview.
Is this question asked at entry level?
It is marked Hard. It suits engineers preparing for senior interviews, where you are expected to drive the discussion and go deep on trade-offs.
What should I cover first?
Start with the workloads, the availability target and the security and cost limits. Agree on scope with the interviewer before you design anything.
Can I practise it for free?
It is a premium question. Sign up and unlock it once for 10 credits; it then stays unlocked. When you finish, Lala, your personalized AI mentor, can review your design for 30 credits.

Related questions

Updated · Written by the SevyDevy team

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