VM sizes and series (B, D, E, F) in Azure - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding Azure B-series VM burst behavior

Which statement best describes the behavior of Azure B-series VMs when they use their CPU credits?

A B-series VMs accumulate CPU credits when idle and use them to burst above the baseline CPU performance when needed.

B B-series VMs have fixed CPU performance and do not accumulate or use CPU credits.

C B-series VMs burst CPU performance only when connected to a premium storage account.

D B-series VMs automatically upgrade to D-series when CPU usage exceeds baseline.

💡 Hint

Think about how burstable VMs manage CPU usage over time.

B-series VMs accumulate CPU credits during low usage periods and use these credits to burst above their baseline CPU performance when demand increases.

❓ Architecture

intermediate

Choosing VM series for memory-intensive workloads

You need to deploy a virtual machine optimized for memory-intensive applications with a balanced CPU-to-memory ratio. Which Azure VM series is the best fit?

A E-series

B D-series

C B-series

D F-series

💡 Hint

Consider which series is designed for high memory capacity.

E-series VMs are optimized for memory-intensive workloads, offering a higher memory-to-CPU ratio compared to other series.

❓ service_behavior

advanced

Performance characteristics of Azure F-series VMs

What is the primary performance characteristic of Azure F-series VMs compared to D-series VMs?

A F-series VMs support burstable CPU credits like B-series.

B F-series VMs have more memory per CPU core than D-series.

C F-series VMs have a higher CPU-to-memory ratio, optimized for compute-intensive workloads.

D F-series VMs are optimized for GPU workloads.

💡 Hint

Think about which VM series is designed for compute power over memory.

F-series VMs provide a higher CPU-to-memory ratio than D-series, making them suitable for compute-intensive tasks.

❓ security

advanced

Security considerations for VM series with ephemeral OS disks

Which Azure VM series supports ephemeral OS disks by default, and what is a key security implication of using ephemeral OS disks?

A D-series; ephemeral OS disks improve security by encrypting data at rest automatically.

B B-series; ephemeral OS disks store data persistently across reboots for security auditing.

C F-series; ephemeral OS disks provide network isolation by default.

D E-series; ephemeral OS disks store OS data in local VM storage and data is lost on deallocation, requiring secure backup strategies.

💡 Hint

Consider which series supports ephemeral OS disks and what happens to data on VM stop/start.

E-series VMs support ephemeral OS disks that store OS data on local VM storage, which is lost when the VM is deallocated. This requires careful backup and security planning.

✅ Best Practice

expert

Optimizing cost and performance for variable workloads

You have a workload with low average CPU usage but occasional spikes. Which VM series and configuration best balances cost and performance?

A Use E-series VMs with premium storage to optimize CPU bursts.

B Use B-series VMs to accumulate CPU credits during low usage and burst during spikes.

C Use F-series VMs and scale out manually during spikes.

D Use D-series VMs with fixed high CPU allocation to handle spikes without bursting.

💡 Hint

Think about which VM series is designed for burstable workloads to save cost.

B-series VMs are designed for workloads with low average CPU usage and occasional bursts, allowing cost savings by using accumulated CPU credits.

Practice

1. Which Azure VM series is best suited for applications that need to handle occasional spikes in CPU usage but are idle most of the time?

easy

A. E series (memory optimized)

B. D series (balanced CPU and memory)

C. B series (burstable VMs)

D. F series (compute optimized)

Solution

1. Step 1: Understand the purpose of B series VMs

   B series VMs are designed for workloads that are idle most of the time but need to burst CPU power occasionally.

2. Step 2: Compare with other series

   D series are balanced, E series focus on memory, and F series focus on CPU but not burstable. So B series fits the description best.

3. Final Answer:

   B series (burstable VMs) -> Option C

4. Quick Check:

   Bursty CPU needs = B series [OK]

Hint: Burstable CPU needs? Pick B series [OK]

Common Mistakes:

• Choosing D series for bursty workloads
• Confusing F series with burstable
• Picking E series which is memory optimized

2. Which of the following is the correct way to describe the F series Azure VMs?

easy

A. Memory optimized VMs for heavy database workloads

B. Burstable VMs for low baseline CPU usage

C. Balanced VMs with equal CPU and memory

D. Compute optimized VMs with higher CPU-to-memory ratio

Solution

1. Step 1: Identify F series characteristics

   F series VMs are compute optimized, meaning they have more CPU power relative to memory.

2. Step 2: Eliminate other options

   Memory optimized describes E series, burstable describes B series, and balanced describes D series.

3. Final Answer:

   Compute optimized VMs with higher CPU-to-memory ratio -> Option D

4. Quick Check:

   F series = compute optimized [OK]

Hint: F series means more CPU power, less memory [OK]

Common Mistakes:

• Mixing F series with memory optimized E series
• Thinking F series are burstable
• Confusing balanced D series with F series

3. You deploy an application that requires high memory but moderate CPU. Which VM series will likely give you the best performance and cost balance?
Options: B, D, E, F

medium

A. B series

B. E series

C. F series

D. D series

Solution

1. Step 1: Match workload needs to VM series

   High memory and moderate CPU needs point to memory optimized VMs.

2. Step 2: Identify E series as memory optimized

   E series VMs are designed for memory-intensive workloads, making them suitable here.

3. Final Answer:

   E series -> Option B

4. Quick Check:

   High memory need = E series [OK]

Hint: High memory? Choose E series [OK]

Common Mistakes:

• Choosing F series which is CPU optimized
• Picking B series which is burstable
• Selecting D series which is balanced but not memory focused

4. A developer chose a B series VM for a high-CPU, always-on web server. What is the main issue with this choice?

medium

A. B series VMs are burstable and may throttle CPU under constant load

B. B series VMs do not support web servers

C. B series VMs have too much memory for web servers

D. B series VMs are more expensive than F series

Solution

1. Step 1: Understand B series limitations

   B series VMs are designed for workloads with low baseline CPU and occasional bursts, not constant high CPU.

2. Step 2: Identify why this is a problem for always-on high CPU

   Constant high CPU usage will cause B series VMs to throttle performance, hurting the web server.

3. Final Answer:

   B series VMs are burstable and may throttle CPU under constant load -> Option A

4. Quick Check:

   Constant high CPU ≠ B series [OK]

Hint: Burstable VMs throttle under constant CPU load [OK]

Common Mistakes:

• Thinking B series can't run web servers
• Assuming B series has too much memory
• Believing B series is more expensive than F series

5. You need to deploy a data analytics application that requires high CPU power and large memory but must also be cost-effective. Which VM series combination should you consider to optimize performance and cost?

hard

A. Use F series for CPU-intensive tasks and E series for memory-intensive tasks

B. Use only B series VMs to save cost

C. Use D series VMs as they balance CPU and memory well

D. Use E series only because memory is most important

Solution

1. Step 1: Analyze workload requirements

   The application needs both high CPU and large memory, which may not be met efficiently by a single VM series.

2. Step 2: Consider splitting workload across VM series

   F series VMs provide high CPU power, while E series VMs provide large memory. Using both can optimize cost and performance.

3. Step 3: Evaluate other options

   B series is burstable and not suitable for heavy workloads. D series is balanced but may not optimize cost as well. E series alone may lack CPU power.

4. Final Answer:

   Use F series for CPU-intensive tasks and E series for memory-intensive tasks -> Option A

5. Quick Check:

   Split CPU and memory needs = F + E series [OK]

Hint: Split CPU and memory tasks across F and E series [OK]

Common Mistakes:

• Choosing only B series to save cost ignoring performance
• Relying solely on D series without optimization
• Using only E series and missing CPU needs