Global infrastructure and migration strategies
Global infrastructure questions are easy points if you keep the building blocks apart. Migration questions are matched by keywords.
Building blocks
| Component | What it is |
|---|---|
| Region | A geographic area with multiple isolated Availability Zones |
| Availability Zone (AZ) | One or more data centers with independent power and networking, linked by low-latency connections |
| Edge location | A site used by Amazon CloudFront and Amazon Route 53 to cache content and answer requests close to users |
| Local Zone | An extension of a Region that places compute and storage near a large city for single-digit millisecond latency |
| AWS Wavelength | AWS compute inside 5G networks |
| AWS Outposts | AWS-managed racks in your data center |
Each Region is independent. Most services are Regional, and data stays in a Region unless you copy it. When choosing a Region, weigh compliance and data residency, then latency to users, then service availability, then price.
High availability
Use at least two AZs for any workload that must survive a data center failure. For disaster recovery or global users, use more than one Region. Elastic Load Balancing and Amazon EC2 Auto Scaling spread and replace instances across AZs.
The 7 Rs of migration
| Strategy | Meaning |
|---|---|
| Retire | Turn off what is no longer needed |
| Retain | Keep on premises for now |
| Rehost | Lift and shift with no changes |
| Relocate | Move to the cloud at the hypervisor level, for example VMware |
| Repurchase | Switch to a different product, often SaaS |
| Replatform | Small optimizations, such as a managed database |
| Refactor | Re-architect to be cloud-native, for example serverless |
Migration tools
- AWS Application Migration Service rehosts servers.
- AWS Database Migration Service (AWS DMS) moves databases, with the AWS Schema Conversion Tool for changing engines.
- AWS DataSync moves data between on-premises storage and AWS storage services.
- AWS Snowball Edge moves large amounts of data offline and can also run compute in disconnected places.
- AWS Migration Hub tracks progress across tools.
Exam traps
- Edge locations are not Regions or AZs; they do not host your EC2 instances.
- Rehost means no changes at all; moving to a managed service is replatform; rebuilding is refactor.
- A single AZ is a single point of failure even if the instance is large.
- Local Zones and Outposts both bring AWS closer, but only Outposts puts hardware in your own facility.
- Data transfer into AWS is free; transfer between Regions and out to the internet is charged.
Practice questions
Choose an answer, then review the explanation to check your understanding.
1. An application must keep running if an entire data center fails. What is the minimum design that gives this protection within one Region?
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Answer: B.An Availability Zone is one or more data centers, so spreading across multiple Availability Zones survives the loss of one.
2. A company moves a self-managed MySQL database to Amazon RDS for MySQL with no code changes beyond a connection string. Which strategy is this?
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Answer: B.Replatform (lift, tinker and shift) makes a small optimization such as moving to a managed database without changing the architecture.
3. Which factor should a company consider FIRST when choosing a Region for a workload with legal data residency rules?
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Answer: A.Data does not leave a Region unless you move it, so compliance and data residency come first, then latency, service availability and price.
4. A company needs AWS infrastructure and the same APIs inside its own data center. Which service fits?
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Answer: A.AWS Outposts places AWS-managed hardware on premises and uses the same APIs and tools.