Interview questions in Cloud Platforms
Explain the difference between IaaS, PaaS, and SaaS with examples
This tests your grasp of cloud abstraction layers and shared responsibility. A strong answer maps IaaS to raw infrastructure like EC2, PaaS to managed runtimes like Heroku, and SaaS to end-user apps like Gmail.
How does shared responsibility shift between IaaS and SaaS?
Tests your understanding of security ownership across cloud stacks. Strong answer: in IaaS you own OS, apps, and network controls; in SaaS you only own data, identities, endpoints, and accounts while the provider manages the rest.
CapEx vs OpEx in cloud migration
CapEx is large upfront asset spend, OpEx is ongoing pay-as-you-go cost; cloud shifts spending from CapEx to OpEx, trading ownership for flexibility.
IaaS vs PaaS for first cloud migration
IaaS (lift-and-shift) gives control with high ops overhead; PaaS lowers ops but may need refactoring; for a monolith with limited expertise, IaaS lift-and-shift is the lower-risk first step.
Scalability vs elasticity in the cloud
Scalability is the ability to handle more load by adding capacity; elasticity is automatically adding AND removing capacity in real time to match demand.
When hybrid cloud beats public or private
Give a scenario like regulated data plus bursty compute; keep sensitive data and legacy systems on-prem, run scalable or customer-facing workloads in public cloud.
Designing for portability across two clouds
Abstract via containers, Terraform, and open standards; avoid proprietary managed services.
Hybrid cloud bursting from a VMware footprint
Evaluate VMware Cloud on AWS, Azure Arc, Outposts; address connectivity, identity, and data gravity.
Launching a virtual machine in the cloud
Pick image, instance type, network placement and security, attached storage, and access keys.
What a machine image is and why it matters
An image is a frozen template of OS, software, and config; it makes launches identical and fast.
Designing an auto-scaling web tier
Front with a load balancer, define a launch template, an auto-scaling group across AZs, and target-tracking policies.
On-Demand vs Reserved vs Spot pricing
On-Demand for unpredictable bursty work, Reserved or Savings Plans for steady baseline, Spot for interruptible fault-tolerant jobs.
Managing state across ephemeral instances
Keep instances stateless, externalize sessions to Redis, data to managed databases, files to object storage.
The instance metadata service explained
A local endpoint exposing instance identity, region, and temporary role credentials.
Optimizing low-latency VM-to-VM networking
Cluster placement groups, enhanced networking and SR-IOV, larger instances for more bandwidth.
Cost-effective fault-tolerant batch processing
Spot fleets across types, a durable work queue, idempotent checkpointed tasks, retries.
Object vs block vs file storage
Object stores flat keyed blobs over HTTP, block gives raw volumes for one VM, file offers a shared hierarchical mount.
Serving user images securely from object storage
Store images in a private bucket, serve via a CDN with origin access control, use signed URLs for private content.
Diagnosing high I/O wait on a database volume
Check IOPS and throughput against the volume limit, look for burst-credit exhaustion, then move to provisioned IOPS or a larger volume.
Shared file system access across many VMs
Use a managed NFS service like EFS or Filestore; watch per-operation latency, throughput modes, and metadata-heavy small-file workloads.
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