Intermediate interview questions in Cloud Platforms
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 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.
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.
Protecting object storage from accidental loss
Enable versioning, MFA delete or object lock, cross-region replication, and least-privilege policies.
Object storage tiers and lifecycle automation
Tiers trade storage price for retrieval cost and latency; automate with lifecycle rules or intelligent tiering.
Connecting two VPCs privately
VPC peering is simple but non-transitive and full-mesh; a Transit Gateway scales hub-and-spoke; PrivateLink exposes one service narrowly.
Process running but load balancer says unhealthy
The probe path, port, protocol, or expected status may mismatch; a security group may block the probe; the app may be up but not ready.
DNS routing policies for active-passive failover
A failover policy with health checks routes to primary and flips to secondary on failure; keep TTL low; pair with health checks not just policy.
CDN caching for static and dynamic content
Cache static assets with long TTLs and versioned filenames; bypass or short-cache dynamic per-user responses; invalidate via fingerprinted URLs not purges.
Granting a VM scoped storage access without static keys
Attach a least-privilege role or managed identity to the VM so it gets auto-rotating temporary credentials scoped to the bucket.
Service-managed vs customer-managed vs BYOK keys
Service-managed keys are automatic but opaque; CMK gives you control over rotation, policy, and revocation in a KMS; BYOK imports your own key material for compliance.
Automating a no-public-IP governance rule
Use organization-level policy guardrails (SCP, Azure Policy, Org Policy) to deny public IP attachment before creation, applied across all accounts.
Shared responsibility model across service tiers
Provider secures the cloud infrastructure; you secure what you put in it; the line shifts with abstraction. For OS patching, you patch IaaS VMs but the provider patches a managed database OS.
RDS Multi-AZ versus Read Replicas
Multi-AZ is a synchronous standby for failover, replicas are async for read scaling, combine both when needed.
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