The answer is intermittent target group health check failures on the EC2 instances. This is the most likely cause because an Application Load Balancer routes traffic only to healthy targets; when health checks fail intermittently, the ALB periodically deregisters those instances, causing the application to become unreachable during those brief windows. On the AWS Certified SAP on AWS Specialty PAS-C01 exam, this scenario tests your understanding of how ALB health check thresholds and intervals interact with SAP application stability—a common trap is to misdiagnose the issue as a network ACL or security group problem, but the key clue is the word “intermittent” rather than persistent failure. For the search intent “ALB health check failures intermittent unreachability,” remember that the ALB’s health check grace period and failure threshold directly control how quickly an instance is removed from service. Memory tip: think “intermittent = health check flip-flop” to avoid chasing the wrong root cause.
PAS-C01 Technology Practice Question
This PAS-C01 practice question tests your understanding of technology. 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.
A company is running SAP BusinessObjects on AWS. The application is deployed on EC2 instances with an Application Load Balancer. Users are reporting that the application is sometimes unreachable. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The target group health checks are failing intermittently on the EC2 instances.
Intermittent unreachability of an application behind an Application Load Balancer (ALB) is most commonly caused by health checks failing on the target EC2 instances. When health checks fail intermittently, the ALB will periodically mark the instances as unhealthy and stop routing traffic to them, causing the application to become unreachable during those windows. This matches the symptom of 'sometimes unreachable' rather than a persistent failure.
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 target group health checks are failing intermittently on the EC2 instances.
Why this is correct
Unhealthy instances are removed from the load balancer, causing connection failures.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The security group for the instances is not allowing traffic from the load balancer.
Why it's wrong here
If misconfigured, it would be consistently unreachable, not intermittent.
✗
The load balancer is not configured with sticky sessions.
Why it's wrong here
Sticky sessions affect session persistence, not availability.
✗
The Route 53 TTL is too short for DNS resolution.
Why it's wrong here
Short TTL causes more DNS queries but not unavailability.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse intermittent reachability with misconfigured security groups or DNS, but the key phrase 'sometimes unreachable' points directly to a dynamic health check failure rather than a static configuration error.
Detailed technical explanation
How to think about this question
ALB health checks use HTTP/HTTPS or TCP pings to a configured path (e.g., /health) on the target instances. If the application or its dependencies (database, SAP BusinessObjects services) become temporarily overloaded or unresponsive, the health check may fail, causing the ALB to deregister the instance. The ALB's health check interval (default 30 seconds) and unhealthy threshold (default 2 consecutive failures) mean that even a brief spike in latency can cause a window of unreachability. This is a classic scenario where monitoring health check logs and instance metrics (CPU, memory, application logs) is essential to diagnose the root cause.
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 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.
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.
Technology — This question tests Technology — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The target group health checks are failing intermittently on the EC2 instances. — Intermittent unreachability of an application behind an Application Load Balancer (ALB) is most commonly caused by health checks failing on the target EC2 instances. When health checks fail intermittently, the ALB will periodically mark the instances as unhealthy and stop routing traffic to them, causing the application to become unreachable during those windows. This matches the symptom of 'sometimes unreachable' rather than a persistent failure.
What should I do if I get this PAS-C01 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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This PAS-C01 practice question is part of Courseiva's free Amazon Web Services 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 PAS-C01 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.