Interview Questions/Phone Screen/Docker vs Virtual Machines
BeginnerPhone
2 min

Docker vs Virtual Machines

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Interview Question

Explain the key differences between Docker containers and virtual machines. When would you use one over the other?

Key Points to Cover
  • Containers share the host OS kernel, VMs have their own OS
  • Containers are lighter and start faster
  • VMs provide better isolation and security
  • Use containers for microservices, VMs for legacy apps or strong isolation
Evaluation Rubric
Explains architectural differences (kernel sharing)30% weight
Mentions performance differences (startup time, resource usage)30% weight
Provides appropriate use cases for each40% weight
Hints
  • 💡Think about what each technology virtualizes
  • 💡Consider isolation levels and performance
Common Pitfalls to Avoid
  • ⚠️Failing to clearly articulate the 'shared kernel' vs. 'own full OS' distinction for containers and VMs, respectively.
  • ⚠️Overstating the security isolation of containers, or not acknowledging the shared kernel's potential implications.
  • ⚠️Not providing concrete examples or scenarios for *when* to use one technology over the other, just listing differences.
  • ⚠️Confusing the role of a container engine (like Docker Engine) with that of a hypervisor.
  • ⚠️Focusing too much on a single aspect (e.g., just performance) without covering the broader implications of architecture, isolation, and use cases.
Potential Follow-up Questions
  • What about container orchestration?
  • How do you handle persistent data in containers?
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