CV0-002 · Question #407
A cloud administrator is load balancing six VMs on an IaaS cloud service. The organization has an SLA stating the application should be available 99.999% of the time. At present, the six VMs are…
The correct answer is B. Implement and procure six VMs and add them to the three existing availability zones. To meet a 99.999% availability SLA while maintaining required capacity, the administrator should add another six VMs to the existing three availability zones to handle potential zone failures.
Question
A cloud administrator is load balancing six VMs on an IaaS cloud service. The organization has an SLA stating the application should be available 99.999% of the time. At present, the six VMs are handling the load from one region and three availability zones. System baselines have confirmed there must be at least six VMs to handle this load. Given this scenario, which of the following should the administrator recommend to BEST meet these requirements?
Options
- AImplement and procure three VMs and spread them across three availability zones.
- BImplement and procure six VMs and add them to the three existing availability zones.
- CImplement and procure another region and set up three VMs across three availability zones.
- DImplement and procure another region and set up six VMs across three availability zones.
How the community answered
(28 responses)- A18% (5)
- B64% (18)
- C4% (1)
- D14% (4)
Why each option
To meet a 99.999% availability SLA while maintaining required capacity, the administrator should add another six VMs to the existing three availability zones to handle potential zone failures.
Implementing only three additional VMs would result in a total of 9 VMs; if one availability zone fails, the remaining 5 VMs would be below the required 6 VMs for the load, failing to meet the SLA.
To achieve a 99.999% SLA, which implies tolerance for multiple failures, and given that six VMs are the minimum required for the load, doubling the VM count to 12 (6 existing + 6 new) distributed across three availability zones provides sufficient redundancy. This ensures that if an entire availability zone (containing 4 VMs) fails, the remaining two zones still have 8 VMs, exceeding the baseline of 6 required for the load, thus maintaining service availability.
Implementing another region with only three VMs, while providing geographical redundancy, would not meet the baseline load requirement of six VMs if either region operates independently or if a zone fails within the original region.
While implementing another region with six VMs provides significant redundancy, it is often overkill and more expensive than necessary to meet the 99.999% SLA based on the given constraints, as the requirement can be met more cost-effectively within the existing region.
Concept tested: High availability design with availability zones for SLA
Source: https://learn.microsoft.com/en-us/azure/reliability/availability-zones-overview
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