- A
The role policy has an implicit deny because the 'ec2:TerminateInstances' action is not allowed on the specific resource ARN due to missing account ID or region mismatch, or the session credentials have expired.
This option correctly identifies two common causes: expired session credentials or a resource ARN mismatch (missing account ID or region). Both would result in an implicit deny.
- B
The role policy has a condition that requires the instance to have the tag 'Environment' set to 'dev', but the condition is evaluated against the principal, not the resource.
Why wrong: This option is incorrect because IAM policy conditions can evaluate resource tags. The condition is evaluated against the resource, not the principal. The user's action may satisfy the condition, but the error is due to other reasons like ARN mismatch or credential expiry.
- C
The role policy includes 'ec2:Describe*' which grants permission to describe all resources, but that does not include terminate. The condition on TerminateInstances requires the tag, but the user may not have passed the tag condition correctly.
Why wrong: This option is incorrect because the condition on TerminateInstances is based on the resource tag, not on whether the user passed the tag condition. Also, Describe* does not grant terminate permissions.
- D
The policy uses 'ec2:TerminateInstances' with a resource ARN that includes the region and account, but the instance may be in a different region or account.
Why wrong: This option is partially correct in mentioning region/account mismatch, but it does not address credential expiration, which is another likely cause. The error could be due to either reason, so this single reason is not the most complete answer.
IAM Policy Allow and Deny Evaluation — Understanding Implicit Deny and Conditions
This SCS-C02 practice question tests your understanding of infrastructure security. 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.
Refer to the exhibit. A user assumes the role and tries to terminate an instance, but gets an error. The instance i-12345678 has a tag 'Environment' with value 'dev'. What is the most likely reason for the failure?
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 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 role policy has an implicit deny because the 'ec2:TerminateInstances' action is not allowed on the specific resource ARN due to missing account ID or region mismatch, or the session credentials have expired.
The error most likely occurs because the assumed role credentials have expired, or because the policy's resource ARN for ec2:TerminateInstances does not include the correct account ID or region, resulting in an implicit deny. Option A correctly identifies these two possibilities. The instance tag is not the issue here, as the condition for the tag is likely satisfied.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
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 role policy has an implicit deny because the 'ec2:TerminateInstances' action is not allowed on the specific resource ARN due to missing account ID or region mismatch, or the session credentials have expired.
Why this is correct
This option correctly identifies two common causes: expired session credentials or a resource ARN mismatch (missing account ID or region). Both would result in an implicit deny.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
- ✗
The role policy has a condition that requires the instance to have the tag 'Environment' set to 'dev', but the condition is evaluated against the principal, not the resource.
Why it's wrong here
This option is incorrect because IAM policy conditions can evaluate resource tags. The condition is evaluated against the resource, not the principal. The user's action may satisfy the condition, but the error is due to other reasons like ARN mismatch or credential expiry.
- ✗
The role policy includes 'ec2:Describe*' which grants permission to describe all resources, but that does not include terminate. The condition on TerminateInstances requires the tag, but the user may not have passed the tag condition correctly.
Why it's wrong here
This option is incorrect because the condition on TerminateInstances is based on the resource tag, not on whether the user passed the tag condition. Also, Describe* does not grant terminate permissions.
- ✗
The policy uses 'ec2:TerminateInstances' with a resource ARN that includes the region and account, but the instance may be in a different region or account.
Why it's wrong here
This option is partially correct in mentioning region/account mismatch, but it does not address credential expiration, which is another likely cause. The error could be due to either reason, so this single reason is not the most complete answer.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
- Standard ACLs match source addresses.
- Extended ACLs can match source, destination, protocol and ports.
- The first matching ACL entry is used.
- There is usually an implicit deny at the end.
TExam Day Tips
- Check inbound versus outbound direction.
- Read the ACL from top to bottom.
- Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SCS-C02 ACL questions on filtering logic and placement.
- →
Infrastructure Security — study guide chapter
Learn the concepts, then practise the questions
- →
Infrastructure Security practice questions
Targeted practice on this topic area only
- →
All SCS-C02 questions
1,748 questions across all exam domains
- →
AWS Certified Security Specialty SCS-C02 study guide
Full concept coverage aligned to exam objectives
- →
SCS-C02 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Related SCS-C02 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Threat Detection and Incident Response practice questions
Practise SCS-C02 questions linked to Threat Detection and Incident Response.
Security Logging and Monitoring practice questions
Practise SCS-C02 questions linked to Security Logging and Monitoring.
Identity and Access Management practice questions
Practise SCS-C02 questions linked to Identity and Access Management.
Management and Security Governance practice questions
Practise SCS-C02 questions linked to Management and Security Governance.
Infrastructure Security practice questions
Practise SCS-C02 questions linked to Infrastructure Security.
Data Protection practice questions
Practise SCS-C02 questions linked to Data Protection.
SCS-C02 fundamentals practice questions
Practise SCS-C02 questions linked to SCS-C02 fundamentals.
SCS-C02 scenario practice questions
Practise SCS-C02 questions linked to SCS-C02 scenario.
SCS-C02 troubleshooting practice questions
Practise SCS-C02 questions linked to SCS-C02 troubleshooting.
Practice this exam
Start a free SCS-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 SCS-C02 question test?
Infrastructure Security — This question tests Infrastructure Security — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The role policy has an implicit deny because the 'ec2:TerminateInstances' action is not allowed on the specific resource ARN due to missing account ID or region mismatch, or the session credentials have expired. — The error most likely occurs because the assumed role credentials have expired, or because the policy's resource ARN for ec2:TerminateInstances does not include the correct account ID or region, resulting in an implicit deny. Option A correctly identifies these two possibilities. The instance tag is not the issue here, as the condition for the tag is likely satisfied.
What should I do if I get this SCS-C02 question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SCS-C02 ACL questions on filtering logic and placement.
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?
Standard ACLs match source addresses.
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
2 more ways this is tested on SCS-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. Refer to the exhibit. A security engineer is reviewing this IAM policy attached to a user. The user reports that they are able to stop and start instances, but they cannot terminate instances. However, the engineer notices that there is no explicit deny for termination. Why is the user unable to terminate instances?
hard- ✓ A.The policy does not include an explicit Allow for ec2:TerminateInstances.
- B.The second statement's Resource is set to '*' but the Action list does not include termination.
- C.The first statement's Resource element is too restrictive and does not include the termination API call.
- D.The policy has a syntax error that prevents termination from being evaluated.
Why A: Option A is correct because IAM policies operate on an explicit allow model. Even though there is no explicit deny for ec2:TerminateInstances, the user is unable to terminate instances because the policy does not include an explicit Allow action for ec2:TerminateInstances. Without an explicit Allow, the default behavior is to deny the action, regardless of whether a deny statement is present.
Variation 2. A security engineer is reviewing an IAM policy attached to a user. The policy is intended to allow all EC2 actions except deleting volumes in the Production environment. However, the user reports being able to delete volumes that are tagged with Environment=Production. What is the reason for this behavior?
hard- A.The policy is not attached to the correct IAM entity.
- B.The Deny statement should use iam:ResourceTag instead of ec2:ResourceTag.
- ✓ C.The condition in the Deny statement uses StringNotEquals, which denies deletion for non-Production volumes, not Production volumes.
- D.The Allow statement uses a wildcard for the action, which overrides the Deny statement.
Why C: Option C is correct because the Deny statement uses the StringNotEquals condition operator with ec2:ResourceTag/Environment=Production. This means the Deny applies when the tag value is NOT equal to Production, so it denies deletion for non-Production volumes but allows deletion for Production volumes. To deny deletion of Production volumes, the policy should use StringEquals instead of StringNotEquals.
Keep practising
More SCS-C02 practice questions
- A company uses AWS Organizations with multiple accounts. The security team wants to enforce that all Amazon S3 buckets a…
- A company is designing a multi-tier web application on AWS. The web tier must be accessible from the internet, but the a…
- A company is migrating a legacy application to AWS. The application requires two-way communication between the web serve…
- A security engineer is troubleshooting connectivity issues between an Amazon EC2 instance in a VPC and an on-premises se…
- A security engineer is reviewing the SQS queue policy shown in the exhibit. The queue is subscribed to an SNS topic in t…
- A company uses AWS Organizations with multiple accounts. The security team wants to ensure that all IAM users in the pro…
Last reviewed: Jun 25, 2026
This SCS-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 SCS-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.