- A
Update the Auto Scaling group's launch template to use a new AMI and perform a rolling update.
Why wrong: Rolling updates replace instances gradually but may still terminate instances with active sessions.
- B
Use an Auto Scaling group with a lifecycle hook that waits for instance termination.
Why wrong: Lifecycle hooks can delay termination but do not guarantee session completion; ALB connection draining is needed.
- C
Enable connection draining (deregistration delay) on the ALB target group and use lifecycle hooks to wait for the draining period.
Deregistration delay ensures in-flight requests complete; lifecycle hooks provide additional control over termination.
- D
Increase the health check interval and unhealthy threshold on the ALB target group.
Why wrong: This delays removal of unhealthy instances but does not preserve sessions.
Quick Answer
The correct answer is to enable connection draining, also known as deregistration delay, on the ALB target group and pair it with Auto Scaling lifecycle hooks to wait for the draining period. This works because connection draining allows the load balancer to stop sending new requests to an instance being de-registered while still completing any in-flight sessions, preventing the abrupt termination that causes user timeouts. On the AWS Certified DevOps Engineer Professional DOP-C02 exam, this scenario tests your understanding of how to achieve zero-downtime deployments with stateful applications, often appearing as a trap where candidates confuse health check thresholds or launch template updates with session preservation. A common pitfall is assuming Auto Scaling alone handles graceful shutdowns, but it does not—lifecycle hooks are required to pause termination until the draining period expires. Memory tip: think “drain before you drain” — let the ALB drain connections before the instance drains from the ASG.
DOP-C02 Resilient Cloud Solutions Practice Question
This DOP-C02 practice question tests your understanding of resilient cloud solutions. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 a stateful web application on EC2 instances behind an Application Load Balancer. During a deployment, users report session timeouts. What should the DevOps engineer implement to ensure zero-downtime deployments without losing in-flight sessions?
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
Enable connection draining (deregistration delay) on the ALB target group and use lifecycle hooks to wait for the draining period.
Option D is correct because deregistration delay (connection draining) on the ALB target group allows in-flight requests to complete before instances are terminated. Option A is wrong because Auto Scaling groups do not manage session stickiness during deployments. Option B is wrong because updating the launch template does not prevent session loss during replacement. Option C is wrong because gradually increasing health check thresholds does not ensure existing sessions are preserved.
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.
- ✗
Update the Auto Scaling group's launch template to use a new AMI and perform a rolling update.
Why it's wrong here
Rolling updates replace instances gradually but may still terminate instances with active sessions.
- ✗
Use an Auto Scaling group with a lifecycle hook that waits for instance termination.
Why it's wrong here
Lifecycle hooks can delay termination but do not guarantee session completion; ALB connection draining is needed.
- ✓
Enable connection draining (deregistration delay) on the ALB target group and use lifecycle hooks to wait for the draining period.
Why this is correct
Deregistration delay ensures in-flight requests complete; lifecycle hooks provide additional control over termination.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
Increase the health check interval and unhealthy threshold on the ALB target group.
Why it's wrong here
This delays removal of unhealthy instances but does not preserve sessions.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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 DOP-C02 NAT questions on configuration and troubleshooting.
- →
Resilient Cloud Solutions — study guide chapter
Learn the concepts, then practise the questions
- →
Resilient Cloud Solutions practice questions
Targeted practice on this topic area only
- →
All DOP-C02 questions
1,740 questions across all exam domains
- →
AWS Certified DevOps Engineer Professional DOP-C02 study guide
Full concept coverage aligned to exam objectives
- →
DOP-C02 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related DOP-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Configuration Management and IaC practice questions
Practise DOP-C02 questions linked to Configuration Management and IaC.
Resilient Cloud Solutions practice questions
Practise DOP-C02 questions linked to Resilient Cloud Solutions.
Monitoring and Logging practice questions
Practise DOP-C02 questions linked to Monitoring and Logging.
Incident and Event Response practice questions
Practise DOP-C02 questions linked to Incident and Event Response.
Security and Compliance practice questions
Practise DOP-C02 questions linked to Security and Compliance.
SDLC Automation practice questions
Practise DOP-C02 questions linked to SDLC Automation.
DOP-C02 fundamentals practice questions
Practise DOP-C02 questions linked to DOP-C02 fundamentals.
DOP-C02 scenario practice questions
Practise DOP-C02 questions linked to DOP-C02 scenario.
DOP-C02 troubleshooting practice questions
Practise DOP-C02 questions linked to DOP-C02 troubleshooting.
Practice this exam
Start a free DOP-C02 practice session
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Questions learners often ask
What does this DOP-C02 question test?
Resilient Cloud Solutions — This question tests Resilient Cloud Solutions — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Enable connection draining (deregistration delay) on the ALB target group and use lifecycle hooks to wait for the draining period. — Option D is correct because deregistration delay (connection draining) on the ALB target group allows in-flight requests to complete before instances are terminated. Option A is wrong because Auto Scaling groups do not manage session stickiness during deployments. Option B is wrong because updating the launch template does not prevent session loss during replacement. Option C is wrong because gradually increasing health check thresholds does not ensure existing sessions are preserved.
What should I do if I get this DOP-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 DOP-C02 NAT questions on configuration and troubleshooting.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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 →
Same concept, more angles
1 more ways this is tested on DOP-C02
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A company runs a stateless web application on AWS Lambda behind an Application Load Balancer (ALB). During a deployment, the team updates the Lambda function to a new version. Some users report seeing the old version of the application for several minutes after the deployment. What is the MOST likely cause?
hard- A.The Lambda function versions are not immutable, causing a gradual rollout.
- B.Lambda@Edge is overriding the function version at the edge locations.
- C.Amazon CloudFront is caching the old response and has not been invalidated.
- ✓ D.The ALB target group is still pointing to the old Lambda function version due to connection draining.
Why D: Option B is correct because ALB has a warm-up effect and may keep old connections alive, causing traffic to old Lambda versions if the alias is not updated atomically. Option A is wrong because Lambda versions are immutable. Option C is wrong because CloudFront caching is unrelated to ALB. Option D is wrong because Lambda@Edge is not involved in this setup.
Last reviewed: Jun 20, 2026
This DOP-C02 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 DOP-C02 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.