- A
The ALB connection draining is enabled with a very short timeout, causing in-flight connections to be dropped.
Connection draining with a short timeout can cause 503 errors when the ALB stops sending traffic to an instance before in-flight requests complete.
- B
The EC2 instances are running out of memory.
Why wrong: Memory exhaustion would typically cause application errors, not 503 errors from the ALB.
- C
The Auto Scaling group launch configuration uses an AMI that is not compatible with the instance type.
Why wrong: An incompatible AMI would cause instances to fail to launch or be unhealthy, but would not cause intermittent 503 errors.
- D
The ALB health check is misconfigured, causing healthy instances to be marked unhealthy.
Why wrong: Misconfigured health checks would cause the ALB to stop sending traffic to healthy instances, but this would not typically result in 503 errors.
SAP-C02 Continuous Improvement for Existing Solutions Practice Question
This SAP-C02 practice question tests your understanding of continuous improvement for existing solutions. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 runs a web application on EC2 instances behind an Application Load Balancer. Users report intermittent 503 errors. The Auto Scaling group has a minimum of 2 and maximum of 10 instances. CloudWatch metrics show that CPU utilization rarely exceeds 30%. What is the MOST likely cause of the 503 errors?
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.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
The ALB connection draining is enabled with a very short timeout, causing in-flight connections to be dropped.
The 503 errors are likely due to the ALB connection draining setting. If connection draining is enabled and the drain timeout is too short, in-flight requests may be terminated, causing 503 errors. Low CPU utilization suggests the instances are not overloaded.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 ALB connection draining is enabled with a very short timeout, causing in-flight connections to be dropped.
Why this is correct
Connection draining with a short timeout can cause 503 errors when the ALB stops sending traffic to an instance before in-flight requests complete.
Clue confirmation
The clue words "most likely", "minimum / minimize" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
The EC2 instances are running out of memory.
Why it's wrong here
Memory exhaustion would typically cause application errors, not 503 errors from the ALB.
- ✗
The Auto Scaling group launch configuration uses an AMI that is not compatible with the instance type.
Why it's wrong here
An incompatible AMI would cause instances to fail to launch or be unhealthy, but would not cause intermittent 503 errors.
- ✗
The ALB health check is misconfigured, causing healthy instances to be marked unhealthy.
Why it's wrong here
Misconfigured health checks would cause the ALB to stop sending traffic to healthy instances, but this would not typically result in 503 errors.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. 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.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SAP-C02 NAT questions on configuration and troubleshooting.
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Continuous Improvement for Existing Solutions — study guide chapter
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FAQ
Questions learners often ask
What does this SAP-C02 question test?
Continuous Improvement for Existing Solutions — This question tests Continuous Improvement for Existing Solutions — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The ALB connection draining is enabled with a very short timeout, causing in-flight connections to be dropped. — The 503 errors are likely due to the ALB connection draining setting. If connection draining is enabled and the drain timeout is too short, in-flight requests may be terminated, causing 503 errors. Low CPU utilization suggests the instances are not overloaded.
What should I do if I get this SAP-C02 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related SAP-C02 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely", "minimum / minimize". 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?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 20, 2026
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