Question 338 of 1,750
SDLC AutomationhardMultiple SelectObjective-mapped

Recovering from a Failed CloudFormation Stack Update Rollback — ContinueUpdateRollback

This DOP-C02 practice question tests your understanding of sdlc automation. 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 uses AWS CloudFormation with nested stacks to manage a microservices application. The root stack creates a VPC, and nested stacks create ECS services. A developer updates the root stack, but the update fails with 'UPDATE_ROLLBACK_IN_PROGRESS'. The rollback also fails. Which THREE steps should the team take to recover the stack? (Choose THREE.)

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

Use the 'SignalResource' action to send a success signal to the failed resource if it is a custom resource.

Option B is correct because if a custom resource failed during rollback due to a missing success signal, sending a success signal via 'SignalResource' can allow the rollback to proceed. Option D is correct because 'ContinueUpdateRollback' resumes the failed rollback, skipping the problematic resource. Option E is correct because if a resource cannot be deleted (e.g., non-empty S3 bucket), manually fixing it allows the rollback to continue. Option A is incorrect because a stack policy does not fix rollback failures. Option C is incorrect because manually deleting a nested stack outside CloudFormation causes drift and does not resolve the rollback state.

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.

  • Set the stack policy to allow all updates and retry the update.

    Why it's wrong here

    Setting a stack policy does not address the root cause of rollback failure; it only controls update permissions.

  • Use the 'SignalResource' action to send a success signal to the failed resource if it is a custom resource.

    Why this is correct

    If a custom resource failed because it did not receive a required success signal, using 'SignalResource' to send the signal can unblock the rollback and allow it to continue.

    Related concept

    Read the scenario before looking for a memorised answer.

  • Manually delete the failed nested stack from the AWS CloudFormation console.

    Why it's wrong here

    Manually deleting a nested stack outside CloudFormation leads to stack drift and does not resolve the rollback failure; CloudFormation will still consider the nested stack as a resource that failed to delete.

  • Use the 'ContinueUpdateRollback' operation from the AWS CLI or console.

    Why this is correct

    The 'ContinueUpdateRollback' operation is specifically designed to retry rollback from the point of failure, skipping the resource that caused the failure.

    Related concept

    Read the scenario before looking for a memorised answer.

  • If the rollback fails due to a resource that cannot be deleted, manually fix the resource (e.g., delete a non-empty S3 bucket) and then continue rollback.

    Why this is correct

    If a resource cannot be deleted (e.g., non-empty S3 bucket), manually fixing the issue and then continuing the rollback is a valid recovery step.

    Related concept

    Read the scenario before looking for a memorised answer.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often think manually deleting the nested stack (Option C) will fix the root stack, but CloudFormation treats nested stacks as resources, and deleting them outside of CloudFormation leads to drift and unresolved rollback states.

Detailed technical explanation

How to think about this question

The 'ContinueUpdateRollback' operation works by identifying the specific resource that caused the rollback to fail and marking it as 'skip' during the rollback process. This is particularly useful when a resource cannot be deleted due to dependencies (e.g., a non-empty S3 bucket or an RDS instance with deletion protection). Under the hood, CloudFormation uses a state machine to track resource statuses, and continuing the rollback effectively resets the stack to its previous known good state while leaving the problematic resource in place for manual remediation.

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.

Visual reference

Client Recursive Resolver Root DNS (13 root servers) TLD DNS (.com, .org, …) Authoritative example.com query IP addr answer

Quick reference

AWS S3 Storage Class Comparison

Storage ClassMin DurationRetrievalUse Case
S3 StandardNoneImmediateFrequently accessed data
S3 Standard-IA30 daysImmediateInfrequent access, rapid retrieval
S3 One Zone-IA30 daysImmediateNon-critical infrequent data
S3 Intelligent-TieringNoneImmediate–hoursUnknown or changing access patterns
S3 Glacier Instant90 daysMillisecondsArchive with instant retrieval
S3 Glacier Flexible90 daysMinutes–hoursArchive, flexible retrieval
S3 Glacier Deep Archive180 daysHoursLong-term compliance archive

What to study next

Got this wrong? Here's your next step.

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FAQ

Questions learners often ask

What does this DOP-C02 question test?

SDLC Automation — This question tests SDLC Automation — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: Use the 'SignalResource' action to send a success signal to the failed resource if it is a custom resource. — Option B is correct because if a custom resource failed during rollback due to a missing success signal, sending a success signal via 'SignalResource' can allow the rollback to proceed. Option D is correct because 'ContinueUpdateRollback' resumes the failed rollback, skipping the problematic resource. Option E is correct because if a resource cannot be deleted (e.g., non-empty S3 bucket), manually fixing it allows the rollback to continue. Option A is incorrect because a stack policy does not fix rollback failures. Option C is incorrect because manually deleting a nested stack outside CloudFormation causes drift and does not resolve the rollback state.

What should I do if I get this DOP-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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Last reviewed: Jul 4, 2026

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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.