The answer is that the IAM policy is missing the `iam:PassRole` permission. AWS DMS requires this permission to allow the replication instance to assume the IAM role that grants it access to the source and target endpoints. Without `iam:PassRole`, the DMS service cannot securely delegate the necessary permissions—such as reading from the on-premises Oracle database or writing to S3—to the replication instance, causing an access error even when S3 and EC2 permissions are present. On the AWS Certified SAP on AWS Specialty PAS-C01 exam, this scenario tests your understanding of the DMS role delegation model, a common trap where candidates focus on endpoint permissions while overlooking the prerequisite role-passing step. Remember the mnemonic: **DMS can’t dance without a pass**—without `iam:PassRole`, the replication instance never gets the keys to the data.
PAS-C01 Migration Practice Question
This PAS-C01 practice question tests your understanding of migration. 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.
The above IAM policy is attached to an IAM role used by an AWS DMS replication instance. The DMS task is migrating data from an on-premises Oracle database to Amazon S3. The DMS task fails with an access error. What is missing from the policy?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Permissions to pass the IAM role to the DMS replication instance are missing
Option B is correct because DMS needs permissions to read from the source endpoint (Oracle database) but the policy only includes S3 and EC2 permissions. The source endpoint is on-premises, so DMS requires network connectivity, but the error is access error, indicating missing IAM permissions for DMS itself. Actually, DMS requires permissions to create network interfaces and describe endpoints. The most common missing permission is 'dms:CreateEndpoint' and 'dms:DescribeEndpoints'. However, since the task is already created, the issue might be that DMS needs to pass the IAM role to the replication instance. The policy missing 'iam:PassRole' is a common cause. Option A is wrong because S3 permissions are present. Option C is wrong because EC2 permissions are present. Option D is wrong because DMS does not need RDS permissions.
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.
✗
Permissions to describe EC2 instances are missing
Why it's wrong here
The policy includes ec2:DescribeInstances.
✗
Permissions to access Amazon RDS are missing
Why it's wrong here
The source is on-premises, not RDS.
✓
Permissions to pass the IAM role to the DMS replication instance are missing
Why this is correct
DMS needs iam:PassRole to allow the replication instance to assume the role.
Related concept
Standard ACLs match source addresses.
✗
Permissions to write to the S3 bucket are missing
Why it's wrong here
The policy includes s3:PutObject for my-bucket.
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 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.
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 PAS-C01 ACL questions on filtering logic and placement.
Migration — This question tests Migration — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Permissions to pass the IAM role to the DMS replication instance are missing — Option B is correct because DMS needs permissions to read from the source endpoint (Oracle database) but the policy only includes S3 and EC2 permissions. The source endpoint is on-premises, so DMS requires network connectivity, but the error is access error, indicating missing IAM permissions for DMS itself. Actually, DMS requires permissions to create network interfaces and describe endpoints. The most common missing permission is 'dms:CreateEndpoint' and 'dms:DescribeEndpoints'. However, since the task is already created, the issue might be that DMS needs to pass the IAM role to the replication instance. The policy missing 'iam:PassRole' is a common cause. Option A is wrong because S3 permissions are present. Option C is wrong because EC2 permissions are present. Option D is wrong because DMS does not need RDS permissions.
What should I do if I get this PAS-C01 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 PAS-C01 ACL questions on filtering logic and placement.
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 →
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.
This PAS-C01 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 PAS-C01 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.