AZ-104 Question 148
Single answerYou are responsible for deploying a three-tier web application in Azure. The application must remain accessible even if an entire data center in the region becomes unavailable. Which deployment strategy should you use to meet this requirement while ensuring the highest possible SLA?
- A
Deploy all virtual machines (VMs) in the same availability set
- B
Deploy VMs in multiple availability sets within the same data center
- C
Deploy each tier across different availability zones in the same region
- D
Deploy each tier in a single availability zone but use a virtual machine scale set
Show answer and explanation
Correct answer: C
Explanation
Deploying virtual machines across multiple availability zones is essential for ensuring resilience against an entire data center (zone) outage and achieving the highest SLA. While availability sets offer some level of redundancy within a data center, only availability zones can protect against a zone-level failure.
- A. Incorrect.
Using a single availability set provides fault domain and update domain protection but does not protect against a data center (zone) outage.
- B. Incorrect.
Multiple availability sets in the same data center still do not protect against a full data center (zone) failure.
- C. Correct.
Spreading the tiers across different availability zones within a single region ensures zone-level redundancy and the highest possible SLA in case one zone becomes unavailable.
- D. Incorrect.
A virtual machine scale set can help with scaling and distribution across fault domains, but if all VMs are in a single availability zone, it does not protect against a whole zone failure.