The request will fail because an explicit deny always overrides an allow in AWS IAM policy evaluation. Even though the policy allows creating RDS instances with names starting with 'new-', the separate Deny statement targeting the Oracle engine is more specific and takes precedence, blocking the creation of 'new-prod-db' with Oracle Standard Edition Two. This scenario tests your understanding of the IAM policy evaluation logic, a critical concept for the AWS Certified Database Specialty DBS-C01 exam, where questions often present conflicting Allow and Deny statements to trap candidates who overlook the explicit deny rule. A common pitfall is assuming a broad Allow will win, but AWS enforces that any explicit Deny—regardless of order—immediately overrides all Allows. Remember the mnemonic: "Deny is the final word; one Deny kills every Allow heard."
DBS-C01 Deployment and Migration Practice Question
This DBS-C01 practice question tests your understanding of deployment and migration. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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. An IAM policy is attached to a user. The user attempts to create an RDS DB instance named 'new-prod-db' with Oracle Standard Edition Two engine. What will happen?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The request will fail because the Deny condition matches the engine.
The policy has an Allow for db names starting with 'new-' and a Deny for Oracle engine. Since there is an explicit Deny for Oracle, the request will be denied due to the Deny override. The Allow does not apply because the Deny is more specific and takes precedence.
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.
✓
The request will fail because the Deny condition matches the engine.
Why this is correct
Explicit Deny for Oracle denies the action.
Related concept
Static NAT maps one inside address to one outside address.
✗
The request will fail because there is no Allow for 'new-prod-db'.
Why it's wrong here
There is an Allow for names starting with 'new-', but Deny overrides.
✗
The request will succeed because the Allow matches the name pattern.
Why it's wrong here
The Deny overrides the Allow.
✗
The request will succeed because the Deny is not effective for 'new-prod-db'.
Why it's wrong here
Deny applies to all resources with condition.
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 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 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 DBS-C01 NAT questions on configuration and troubleshooting.
Deployment and Migration — This question tests Deployment and Migration — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The request will fail because the Deny condition matches the engine. — The policy has an Allow for db names starting with 'new-' and a Deny for Oracle engine. Since there is an explicit Deny for Oracle, the request will be denied due to the Deny override. The Allow does not apply because the Deny is more specific and takes precedence.
What should I do if I get this DBS-C01 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 DBS-C01 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
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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. An IAM policy is attached to a user who is deploying an RDS database. The user attempts to create a DB instance named 'my-database' using the AWS CLI. Which statement is true?
medium
A.The user cannot create the DB instance because the Deny statement applies to all actions
B.The user cannot create the DB instance because the resource ARN does not exist yet
C.The user cannot create the DB instance because of an error in the policy
✓ D.The user can create the DB instance
Why D: The policy allows rds:CreateDBInstance on the specific DB instance and allows rds:CreateDBSubnetGroup on all resources. There is a Deny on ModifyDBInstance, but that action is not performed. The user can create the DB instance. Option A is incorrect because the Deny does not prevent creation. Option C is incorrect because the policy allows creation. Option D is incorrect because the policy is valid.
Variation 2. Refer to the exhibit. An IAM policy is attached to a user. The user tries to delete a database instance named 'prod-mydb' in us-east-1. What will happen?
medium
A.The delete will be allowed because the Allow statement is broader.
B.The delete will fail with an error because the policy is invalid.
C.The delete will succeed only if the instance is tagged with 'Environment: prod'.
✓ D.The delete will be denied because the Deny statement explicitly matches the resource.
Why D: The Deny statement applies to all resources matching 'prod-*', so the delete action is denied for 'prod-mydb'. Even though the Allow statement permits delete, an explicit Deny overrides any Allow. Option B is correct. Option A (Allowed) ignores the Deny. Option C (Error) is not correct because the policy is valid. Option D (Only if tagged) is not in the policy.
Variation 3. Refer to the exhibit. An IAM policy is attached to a user who needs to deploy an RDS MySQL instance. After creating the instance, the user tries to modify it to enable deletion protection, but the action fails. What is the most likely reason?
medium
A.The user does not have permission to describe instances.
B.The resource ARN is not specified in the policy.
✓ C.The user does not have permission to enable deletion protection.
D.The user does not have permission to create the instance.
Why C: Option B is correct because the policy does not include rds:ModifyDBInstance permission. Option A is wrong because deletion protection is a modification. Option C is wrong because the policy allows Create. Option D is wrong because the user has Describe permission.
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Question Discussion
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