Interview practice

Cloud Engineer (AWS / Azure)

5–8 years · Senior — AWS / Azure · Networking · IAM · Cost · Serverless · Storage

technical Serverless 1 of 6

A serverless function is timing out after 30 seconds when processing large payloads. What are your options for addressing this, and what are the implications of each?

What a strong answer covers

Considers increasing the function timeout setting; evaluates breaking the workload into smaller batches; examines using an asynchronous processing model with SQS or EventBridge; discusses implications of increased costs with larger timeouts; mentions potential architectural changes like using AWS Step Functions for orchestration.

The follow-up you would get

What are the drawbacks of increasing the timeout?

Could you have answered that?

scenario Architecture Design 2 of 6

Your application needs to handle a sudden spike in traffic due to a marketing campaign. How do you ensure scalability and performance during this period?

What a strong answer covers

Enables auto-scaling for compute resources; configures load balancers to distribute traffic; caches frequently accessed data using a CDN or in-memory store; implements database read replicas to offload queries; sets up monitoring for real-time adjustments.

The follow-up you would get

The load balancer is underutilised, but the application is still slow. What other factors might be causing this, and how do you investigate?

Could you have answered that?

technical Design 3 of 6

You need to design a highly available architecture for a web application running on AWS with an RDS backend. What key components do you include, and why?

What a strong answer covers

Incorporates Multi-AZ RDS for database redundancy; uses an Application Load Balancer across multiple EC2 instances; employs Auto Scaling for handling traffic spikes; ensures that resources are distributed across multiple Availability Zones; mentions implementing Route 53 for DNS failover.

The follow-up you would get

What are the costs involved with Multi-AZ deployments?

Could you have answered that?

technical Cloud costs 4 of 6

Your monthly cloud bill has unexpectedly increased by 30% over the last month. You have a serverless architecture. What steps do you take to identify the cause, and what metrics do you analyse first?

What a strong answer covers

Checks AWS Cost Explorer or Azure Cost Management for service breakdown; reviews Lambda or Function App invocation counts and duration; examines any changes in API Gateway or event source triggers; assesses the data transfer costs; looks for new resources provisioned or unexpected spikes in usage.

The follow-up you would get

What specific changes in invocation patterns could lead to increased costs?

Could you have answered that?

technical Storage 5 of 6

You have a large dataset stored in Azure Blob Storage, and your application is facing performance issues when retrieving data. What steps do you take to optimise access?

What a strong answer covers

Investigates the access tiers of the Blob Storage; assesses the use of Azure CDN for caching frequently accessed blobs; considers partitioning the dataset for better performance; examines the network bandwidth and latency; explores whether using Azure Data Lake Storage would be beneficial for analytics workloads.

The follow-up you would get

How would you determine if the CDN is effectively reducing latency?

Could you have answered that?

ownership A migration that faced challenges 6 of 6

Describe a migration you led that did not go as planned. What were the main issues, and how did you address them?

What a strong answer covers

Identifies specific migration objectives and constraints; details major challenges encountered during the migration process; explains how issues were diagnosed and resolved in real time; mentions any changes to the original plan and outcomes; reflects on lessons learned for future migrations.

The follow-up you would get

What would you do differently if faced with a similar situation again?

Could you have answered that?

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