DVA-C02 Troubleshooting and Optimization Practice Question
This DVA-C02 practice question tests your understanding of troubleshooting and optimization. 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.
Network Topology
A developer invoked a Lambda function and saw the above output. What is the root cause of the error?
Network Topology
A
The Lambda function lacks permission to access the event payload.
Why wrong: Permissions affect access to AWS resources, not event data.
B
The function code expects a property that is missing from the event payload.
The code tries to access 'length' on undefined, meaning expected property not in event.
C
The Lambda function's handler name is incorrect.
Why wrong: The function started executing, so handler is correct.
D
The Lambda function timed out.
Why wrong: No timeout error; function ran and threw an exception.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The function code expects a property that is missing from the event payload.
The error 'Cannot read property 'length' of undefined' indicates that the code tries to access the 'length' property of an undefined object, meaning the event payload lacks an expected property. Therefore, Option B is correct. Option A is incorrect because permission to access the event payload is not the issue; the function can access the event but expects a specific property. Option C is incorrect because if the handler name were wrong, the function would not start at all. Option D is incorrect because there is no timeout error; the function ran and encountered a runtime error.
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.
✗
The Lambda function lacks permission to access the event payload.
Why it's wrong here
Permissions affect access to AWS resources, not event data.
✓
The function code expects a property that is missing from the event payload.
Why this is correct
The code tries to access 'length' on undefined, meaning expected property not in event.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Lambda function's handler name is incorrect.
Why it's wrong here
The function started executing, so handler is correct.
✗
The Lambda function timed out.
Why it's wrong here
No timeout error; function ran and threw an exception.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 media company stores terabytes of video archives that are accessed once a year for audit purposes. Moving these objects to a cold storage tier (Azure Archive, S3 Glacier, or Google Nearline) costs a fraction of hot storage. Questions like this test whether you understand storage tiers, access frequency tradeoffs, and retrieval latency requirements.
Quick reference
Cloud Service Model Comparison
Model
You Manage
Provider Manages
Examples
IaaS
OS, runtime, apps, data
Hardware, hypervisor, networking
EC2, Azure VMs, GCP Compute Engine
PaaS
Apps and data
OS, runtime, middleware, hardware
Elastic Beanstalk, Azure App Service
SaaS
Data and settings only
Everything else
Microsoft 365, Salesforce, Workday
FaaS / Serverless
Function code only
Infra, scaling, runtime
Lambda, Azure Functions, Cloud Run
CaaS
Containers and apps
Kubernetes, OS, hardware
EKS, AKS, GKE
What to study next
Got this wrong? Here's your next step.
Identify which DVA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Troubleshooting and Optimization — This question tests Troubleshooting and Optimization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The function code expects a property that is missing from the event payload. — The error 'Cannot read property 'length' of undefined' indicates that the code tries to access the 'length' property of an undefined object, meaning the event payload lacks an expected property. Therefore, Option B is correct. Option A is incorrect because permission to access the event payload is not the issue; the function can access the event but expects a specific property. Option C is incorrect because if the handler name were wrong, the function would not start at all. Option D is incorrect because there is no timeout error; the function ran and encountered a runtime error.
What should I do if I get this DVA-C02 question wrong?
Identify which DVA-C02 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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