Welcome back to our AWS Cloud Engineer Interview Series!
In Part 1, we covered advanced scenario-based and behavioral questions—touching on VPC design, security best practices, and troubleshooting strategies.
In this Part 2 installment, we shift focus to core AWS fundamentals that interviewers expect you to know thoroughly.
You’ll go through ten targeted questions covering compute, storage, and database services—along with structured answer approaches and real-world framing.
1. EC2 Instance Families
Question: Explain the differences between General Purpose, Compute Optimized, and Memory Optimized EC2 instance families.
How to Answer
- General Purpose (t3, m5): Balanced CPU, memory, network
Use case: Web servers, small databases, dev/test - Compute Optimized (c5): High CPU-to-memory ratio
Use case: Batch jobs, HPC, encoding - Memory Optimized (r5): High memory-to-CPU ratio
Use case: Redis, analytics
Tip: Mention a real workload where you selected the instance type.
2. Pricing Models
Question: Describe On-Demand, Reserved, and Spot pricing.
- On-Demand: Flexible, no commitment
- Reserved: Lower cost, long-term commitment
- Spot: Cheapest, but interruptible
Tip: Mention cost optimization strategies like mixed Auto Scaling.
3. Auto Scaling
Question: How does an Auto Scaling group work?
- Launch Template
- Capacity settings (min/max/desired)
- Scaling policies (target tracking, step, scheduled)
- Health checks and replacement
Example: Maintaining CPU at ~50% using target tracking.
4. S3 vs EBS
- S3: Object storage (logs, backups, media)
- EBS: Block storage (databases, OS volumes)
5. Amazon EFS
Managed file storage (NFS) accessible across multiple EC2 instances.
Use cases: Shared storage, distributed workloads
6. S3 Glacier
- Expedited: Minutes
- Standard: Hours
- Bulk: Lowest cost, longest time
7. RDS vs Read Replicas
- Multi-AZ: High availability (failover)
- Read Replicas: Read scaling
8. DynamoDB Design
- Partition keys distribute load
- Use GSIs for flexible queries
- Avoid hot partitions
9. Aurora Advantages
- Higher performance
- Auto-scaling storage
- Built-in fault tolerance
10. Choosing the Right Database
Scenario: Flexible schema + low latency → DynamoDB
Alternative: Aurora Serverless for relational needs
General Answering Tips
- Be specific: Mention services and numbers
- Use STAR: For scenarios
- Quantify: Show impact
- Clarify: Ask assumptions
- Stay honest: Show learning ability
Good luck—you’ve got this!
