The answer is to monitor the SurgeQueueLength metric and look for sustained high values. This metric tracks the number of requests queued by the Application Load Balancer because it cannot immediately route them to a healthy target; when the ALB is overwhelmed, requests pile up in the queue rather than being processed, directly causing increased latency. On the AWS Certified Developer Associate DVA-C02 exam, this tests your ability to isolate performance bottlenecks between the load balancer and the backend—a common trap is confusing SurgeQueueLength with RequestCount or TargetResponseTime, which point to backend issues instead. Remember that a high SurgeQueueLength means the ALB itself is the bottleneck, not the EC2 instances. Memory tip: think of the queue as a waiting room—if it’s full, the door (ALB) is the problem, not the people inside.
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.
An application running on Amazon EC2 instances behind an Application Load Balancer (ALB) is experiencing increased latency. The developer suspects the ALB is the bottleneck. How can the developer confirm this using CloudWatch metrics?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Monitor the SurgeQueueLength metric and look for sustained high values.
The SurgeQueueLength metric tracks the number of requests that are queued by the ALB because it cannot route them to a healthy target. A sustained high value indicates that the ALB is overwhelmed and requests are waiting, which directly confirms the ALB as the bottleneck causing increased latency.
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.
✗
Monitor the HealthyHostCount metric and ensure it is equal to the number of instances.
Why it's wrong here
HealthyHostCount indicates target health, not ALB latency.
✓
Monitor the SurgeQueueLength metric and look for sustained high values.
Why this is correct
High SurgeQueueLength means requests are queued, causing latency.
Related concept
Read the scenario before looking for a memorised answer.
✗
Monitor the TargetResponseTime metric and compare it to the client's perspective.
Why it's wrong here
TargetResponseTime measures backend response time, not ALB delay.
✗
Monitor the RequestCount metric and check if it exceeds the ALB's limit.
Why it's wrong here
RequestCount shows request volume but not latency at ALB.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse SurgeQueueLength with backend metrics like TargetResponseTime, assuming latency must come from the targets rather than the load balancer's internal queuing.
Trap categories for this question
Command / output trap
RequestCount shows request volume but not latency at ALB.
Detailed technical explanation
How to think about this question
Under the hood, the ALB uses a shared queue per listener to hold incoming requests when all targets are busy or unhealthy. The SurgeQueueLength metric is emitted every minute and a sustained value above 1024 indicates the ALB is unable to keep up, leading to increased latency or eventual 503 responses. In real-world scenarios, a sudden spike in traffic or a slow target response can cause the queue to build up, even if the targets themselves are healthy.
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.
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: Monitor the SurgeQueueLength metric and look for sustained high values. — The SurgeQueueLength metric tracks the number of requests that are queued by the ALB because it cannot route them to a healthy target. A sustained high value indicates that the ALB is overwhelmed and requests are waiting, which directly confirms the ALB as the bottleneck causing increased latency.
What should I do if I get this DVA-C02 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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