- A
Increase the number of AKS nodes to handle peak traffic and reduce resource contention.
Why wrong: This treats the symptom, not the cause, and may not address connection pooling.
- B
Review the application code to ensure that Redis and SQL connections are properly opened and closed using 'using' statements.
Why wrong: While important, this is time-consuming and should follow telemetry analysis.
- C
Run a load test against the application to reproduce the issue and monitor system counters.
Why wrong: Load testing may not replicate production conditions and could introduce additional load.
- D
Use Application Insights 'Dependency' performance blade to analyze call duration percentiles and identify whether the bottleneck is in Redis or SQL. Then adjust connection pool sizes accordingly.
This allows data-driven diagnosis of which dependency is causing the delay.
AZ-400 Implement an instrumentation strategy Practice Question
This AZ-400 practice question tests your understanding of implement an instrumentation strategy. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
You are a DevOps engineer for a large e-commerce company. The company uses Azure DevOps for CI/CD and Application Insights for monitoring. The application is a .NET Core 6 microservice running on Azure Kubernetes Service (AKS) with a Redis cache and Azure SQL Database. Recently, the operations team noticed that the application's response time has degraded significantly during peak traffic hours. Application Insights shows an increase in server-side dependency call duration to Redis and SQL, but no increase in exceptions. The team suspects a connection pooling issue. You have been asked to diagnose and fix the problem. Which approach should you take first?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"first"Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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
Use Application Insights 'Dependency' performance blade to analyze call duration percentiles and identify whether the bottleneck is in Redis or SQL. Then adjust connection pool sizes accordingly.
Option D is correct because the first step in diagnosing a connection pooling issue is to analyze the dependency performance data in Application Insights. The 'Dependency' blade provides detailed percentiles (e.g., P50, P95, P99) for Redis and SQL call durations, allowing you to pinpoint which dependency is the bottleneck. Once identified, you can adjust the connection pool size (e.g., Max Pool Size in SQL connection string or Redis multiplexer settings) to match the peak concurrency demands without overwhelming the database or cache.
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.
- ✗
Increase the number of AKS nodes to handle peak traffic and reduce resource contention.
Why it's wrong here
This treats the symptom, not the cause, and may not address connection pooling.
- ✗
Review the application code to ensure that Redis and SQL connections are properly opened and closed using 'using' statements.
Why it's wrong here
While important, this is time-consuming and should follow telemetry analysis.
- ✗
Run a load test against the application to reproduce the issue and monitor system counters.
Why it's wrong here
Load testing may not replicate production conditions and could introduce additional load.
- ✓
Use Application Insights 'Dependency' performance blade to analyze call duration percentiles and identify whether the bottleneck is in Redis or SQL. Then adjust connection pool sizes accordingly.
Why this is correct
This allows data-driven diagnosis of which dependency is causing the delay.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the issue is a code bug (Option B) or infrastructure scaling (Option A), but the question explicitly states no exceptions and a connection pooling suspicion, so the correct first diagnostic step is to analyze existing telemetry to confirm the bottleneck before making changes.
Detailed technical explanation
How to think about this question
Connection pooling in .NET Core for SQL Server uses a default Max Pool Size of 100, while StackExchange.Redis (the common Redis client) uses a default connection multiplexer that can handle up to 50 concurrent threads per connection. During peak traffic, if the number of concurrent requests exceeds these limits, threads queue up waiting for a connection, causing increased dependency call duration without exceptions. Application Insights tracks dependency call duration percentiles, which can reveal tail latency spikes (e.g., P99 > 1 second) that indicate pool exhaustion, whereas average duration might remain low.
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
A cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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-400 question test?
Implement an instrumentation strategy — This question tests Implement an instrumentation strategy — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use Application Insights 'Dependency' performance blade to analyze call duration percentiles and identify whether the bottleneck is in Redis or SQL. Then adjust connection pool sizes accordingly. — Option D is correct because the first step in diagnosing a connection pooling issue is to analyze the dependency performance data in Application Insights. The 'Dependency' blade provides detailed percentiles (e.g., P50, P95, P99) for Redis and SQL call durations, allowing you to pinpoint which dependency is the bottleneck. Once identified, you can adjust the connection pool size (e.g., Max Pool Size in SQL connection string or Redis multiplexer settings) to match the peak concurrency demands without overwhelming the database or cache.
What should I do if I get this AZ-400 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: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
This AZ-400 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AZ-400 exam.
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