Question 67 of 999

Design infrastructure solutions →hardMultiple ChoiceObjective-mapped

Quick Answer

The answer is Azure Virtual Machine Scale Sets with a Proximity Placement Group. This configuration guarantees that all VMs for a single HPC job are physically co-located within the same Azure datacenter rack or cluster, reducing inter-VM network latency to under 10 microseconds—a critical requirement for MPI communication. A Proximity Placement Group (PPG) forces the Azure fabric to place VMs as close together as possible, minimizing the physical distance data must travel, which is the only way to achieve the ultra-low latency needed for tightly coupled HPC workloads. On the AZ-305 exam, this scenario tests your understanding of how to optimize network performance for specialized compute jobs, and a common trap is choosing Availability Sets or Availability Zones, which prioritize fault tolerance over proximity and can actually increase latency. Remember the mnemonic: “PPG for Ping-Pong”—if your workload needs to ping-pong data between VMs in microseconds, you need a Proximity Placement Group inside a Scale Set.

AZ-305 Design infrastructure solutions Practice Question

This AZ-305 practice question tests your understanding of design infrastructure solutions. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A company runs a high-performance computing (HPC) workload on Azure that requires extremely low latency (under 10 microseconds) between multiple VMs for MPI communication. The VMs are part of a single job and must be placed together to minimize network latency. Which VM deployment option should they use?

Clue words in this question

Noticing these words before you look at the options changes how you read each choice.

Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.

Question 1hardmultiple choice

Full question →

A
Azure Virtual Machine Scale Sets with a Proximity Placement Group
Proximity Placement Groups (PPG) co-locate VMs in the same datacenter region, providing ultra-low latency required for MPI workloads. VMSS allows scaling out while staying in the PPG.
B
Azure Availability Sets
Why wrong: Availability Sets spread VMs across multiple fault domains and update domains, compromising co-location and increasing latency beyond the requirement.
C
Azure Virtual Machine Scale Sets across Availability Zones
Why wrong: Availability Zones place VMs in separate physical locations, which adds network latency that exceeds the sub-10 microsecond requirement.
D
Azure Kubernetes Service (AKS)
Why wrong: AKS adds orchestration overhead and does not guarantee the low-latency placement needed for tightly coupled HPC workloads.

Full breakdown with real-world context →

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

Azure Virtual Machine Scale Sets with a Proximity Placement Group

A Proximity Placement Group (PPG) within a Virtual Machine Scale Set ensures that all VMs are physically located as close as possible within an Azure datacenter, reducing network latency to under 10 microseconds for MPI communication. This is the only option that guarantees co-location of VMs for a single HPC job, as PPGs minimize inter-VM latency by placing VMs in the same rack or cluster.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✓
Azure Virtual Machine Scale Sets with a Proximity Placement Group
Why this is correct
Proximity Placement Groups (PPG) co-locate VMs in the same datacenter region, providing ultra-low latency required for MPI workloads. VMSS allows scaling out while staying in the PPG.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Azure Availability Sets
Why it's wrong here
Availability Sets spread VMs across multiple fault domains and update domains, compromising co-location and increasing latency beyond the requirement.
✗
Azure Virtual Machine Scale Sets across Availability Zones
Why it's wrong here
Availability Zones place VMs in separate physical locations, which adds network latency that exceeds the sub-10 microsecond requirement.
✗
Azure Kubernetes Service (AKS)
Why it's wrong here
AKS adds orchestration overhead and does not guarantee the low-latency placement needed for tightly coupled HPC workloads.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often confuse Availability Sets (which provide high availability) with Proximity Placement Groups (which provide low latency), or assume that Availability Zones offer sufficient performance for HPC, ignoring the significant latency penalty of inter-zone communication.

Detailed technical explanation

How to think about this question

Proximity Placement Groups work by assigning VMs to the same Azure Fabric cluster, leveraging the InfiniBand network for RDMA (Remote Direct Memory Access) communication, which achieves sub-10-microsecond latency essential for MPI workloads like weather modeling or molecular dynamics. Under the hood, Azure uses a non-blocking fat-tree topology for InfiniBand, and PPGs ensure that all VMs are within the same switch domain, avoiding cross-switch hops that would increase latency. In real-world scenarios, HPC jobs such as computational fluid dynamics (CFD) or genomic sequencing require this co-location to avoid MPI timeout errors or performance degradation.

KKey Concepts to Remember

Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.

TExam Day Tips

Watch for words such as best, first, most likely and least administrative effort.
Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this AZ-305 question test?

Design infrastructure solutions — This question tests Design infrastructure solutions — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Azure Virtual Machine Scale Sets with a Proximity Placement Group — A Proximity Placement Group (PPG) within a Virtual Machine Scale Set ensures that all VMs are physically located as close as possible within an Azure datacenter, reducing network latency to under 10 microseconds for MPI communication. This is the only option that guarantees co-location of VMs for a single HPC job, as PPGs minimize inter-VM latency by placing VMs in the same rack or cluster.

What should I do if I get this AZ-305 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Are there clue words in this question I should notice?

Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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