The answer is that the policy does not include ec2:RunInstances in the Action list. This is the most likely reason for an explicitDeny in the IAM policy simulator output because the simulator evaluates the effective permissions of a policy; when an action like ec2:RunInstances is not explicitly allowed, and no other policy grants it, the simulator marks it as an explicit deny rather than an implicit deny. On the AWS Certified Security Specialty SCS-C02 exam, this concept tests your understanding of how the simulator distinguishes between actions that are forbidden by a Deny statement and those simply not listed in an Allow statement—a common trap is confusing an explicit deny from the simulator with a Deny effect in the policy. Remember, the simulator’s explicitDeny flag means the action is not allowed by the policy being tested, not that a Deny statement exists. A helpful memory tip: if it’s not in the Allow list, the simulator calls it explicitDeny.
SCS-C02 Identity and Access Management Practice Question
This SCS-C02 practice question tests your understanding of identity and access management. 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.
Network Topology
Refer to the exhibit. A security engineer runs the 'simulate-custom-policy' command to test a policy. The output shows 'explicitDeny' for ec2:RunInstances. What is the most likely reason?
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 policy does not include ec2:RunInstances in the Action list
Option A is correct because the policy only allows Describe actions, and RunInstances is not allowed, resulting in an explicit deny from the simulation. Option B is incorrect because the policy does not deny. Option C is incorrect because the policy allows Describe* but not RunInstances. Option D is incorrect because there is no resource restriction.
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 policy does not include ec2:RunInstances in the Action list
Why this is correct
The policy only allows ec2:Describe*, so any action not matching is denied.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Standard ACLs match source addresses.
✗
The policy includes an explicit Deny statement for ec2:RunInstances
Why it's wrong here
The policy does not have a Deny statement.
✗
The policy allows ec2:Describe* but the action ec2:RunInstances is not a Describe action
Why it's wrong here
That is true, but the simulation returns 'explicitDeny' because the policy doesn't allow it.
✗
The policy uses a Resource of '*' which does not include the required resources
Why it's wrong here
Resource '*' includes all resources.
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 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. 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. 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 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.
Identity and Access Management — This question tests Identity and Access Management — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: The policy does not include ec2:RunInstances in the Action list — Option A is correct because the policy only allows Describe actions, and RunInstances is not allowed, resulting in an explicit deny from the simulation. Option B is incorrect because the policy does not deny. Option C is incorrect because the policy allows Describe* but not RunInstances. Option D is incorrect because there is no resource restriction.
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 →
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 security engineer runs the IAM policy simulator with a custom policy. The output shows the above. Which statement is true about the policy?
medium
A.The policy allows iam:DeleteUser but denies iam:CreateUser.
B.The policy allows all actions by default.
✓ C.The policy contains a statement that explicitly denies iam:DeleteUser.
D.The policy has no effect because the simulator returned errors.
Why C: The simulator indicates 'explicitDeny' for DeleteUser, meaning a deny statement exists. Option A is correct. Option B is wrong because there is a deny. Option C is wrong because CreateUser is allowed. Option D is wrong because simulator shows explicit deny.
Last reviewed: Jun 20, 2026
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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.
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