2.1 - Cloud migration strategies (the 6 Rs)
Cloud+ CV0-004 objective 2.1 covers migration strategies, often framed as the 6 Rs. Rehost (lift and shift) moves a VM to the cloud unchanged, without redesigning it - the fastest, lowest-effort option. Replatform makes minor tweaks during migration, such as moving a database to a managed service, for some benefit without a full rewrite. Repurchase replaces a self-hosted app with an equivalent SaaS product. Refactor rewrites the application to be cloud-native, the most effort but the most benefit. Retire decommissions an old app instead of moving it, and retain keeps a workload on-premises for now. You should match a described goal - speed, minor optimisation, buying SaaS, rewriting, or dropping an app - to the right R. Expect scenario questions that describe how an app is moved or not and ask which migration strategy it is.
Move unchanged (lift and shift) = rehost. Minor tweaks (e.g. managed DB) = replatform. Swap for a SaaS product = repurchase. Rewrite cloud-native = refactor. Decommission = retire. Keep on-prem = retain.
Practice questions
1. Moving a VM to the cloud unchanged, without redesigning it, is which migration strategy?
- Refactor
- Replatform
- Rehost (correct answer)
- Retire
Rehost (lift-and-shift) moves a workload as-is. Replatform makes minor optimizations; refactor re-architects the app; retire decommissions it.
2. An old app is decommissioned instead of moving it to the cloud. Which of the 6 Rs is this?
- Rehost
- Retire (correct answer)
- Retain
- Repurchase
Retire means shutting down an application no longer needed, cutting cost and risk. Retain keeps it as-is on-prem; repurchase swaps it for a SaaS product.
3. Making minor tweaks such as moving a database to a managed service while migrating is which R?
- Rehost as-is
- Refactor completely
- Replatform (correct answer)
- Retire fully
Replatform (lift-tinker-shift) makes small optimizations like adopting a managed DB without redesigning the app. Refactor re-architects it; rehost moves it unchanged.
4. Replacing a self-hosted app with an equivalent SaaS product during migration is which R?
- Rehost as-is
- Repurchase (correct answer)
- Refactor fully
- Retain in place
Repurchase means dropping the old app and buying a SaaS replacement (for example moving to a hosted CRM). Refactor rewrites the app; retain leaves it where it is.
5. Re-architecting a monolith into cloud-native microservices during migration is which R?
- Rehost
- Replatform
- Refactor (correct answer)
- Retain
Refactor (re-architect) redesigns the app to be cloud-native, the most effort but most cloud benefit. Replatform makes only minor tweaks; rehost moves the app unchanged.
6. You need at least 60 usable host addresses in a subnet. Which prefix is the smallest that fits?
- /27
- /26 (correct answer)
- /25
- /24
A /26 gives 64 addresses, minus network and broadcast leaves 62 usable, covering 60. A /27 gives only 30 usable, too few; larger blocks waste space.