I have been on both sides of the cloud architect interview table. As a hiring manager at Lockheed Martin and Cigna Healthcare, I conducted over 200 technical interviews for cloud architecture roles.
Foundational Architecture Questions
1. What is the difference between high availability and fault tolerance?
High availability minimizes downtime through redundancy. A system with 99.99% availability is highly available. It may experience brief interruptions during failover.
Fault tolerance means the system continues operating without any interruption when a component fails. It requires active-active redundancy.
2. Explain the CAP theorem and how it applies to cloud database selection.
The CAP theorem states a distributed system can guarantee at most two of: Consistency, Availability, Partition tolerance.
- CP systems (DynamoDB strongly consistent, Cloud Spanner): Use for financial transactions.
- AP systems (DynamoDB eventually consistent, Cassandra): Use for social feeds, session stores.
3. How do you design a multi-region active-active architecture?
Key challenges: data replication, conflict resolution, routing.
- Data layer: globally distributed database
- Application layer: identical stacks per region
- Routing: Route 53 latency-based or Cloudflare load balancing
- Conflict resolution: last-writer-wins or vector clocks
4. Containers vs. serverless -- when do you choose each?
| Dimension | Containers | Serverless |
|---|---|---|
| Startup time | Seconds to minutes | Milliseconds to seconds |
| Max execution | Unlimited | 15 minutes (Lambda) |
| Cost model | Per-hour (even idle) | Per-invocation + duration |
| Best for | Long-running services | Event-driven processing |
Read all 30 questions with detailed answers ->
Originally published at Citadel Cloud Management.
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