MLS-C01 Data Engineering Practice Question

Exhibit

Refer to the exhibit.

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:GetObject",
        "s3:PutObject"
      ],
      "Resource": "arn:aws:s3:::my-data-lake/*"
    },
    {
      "Effect": "Deny",
      "Action": "s3:*",
      "Resource": "arn:aws:s3:::my-data-lake/confidential/*",
      "Condition": {
        "StringNotEquals": {
          "aws:PrincipalAccount": "123456789012"
        }
      }
    }
  ]
}
```

Refer to the exhibit. An IAM policy is attached to a data engineering team's role. The team needs to upload data to the 'confidential' prefix in the 'my-data-lake' bucket. However, they are receiving 'AccessDenied' errors. What is the likely cause?

⚠ Common exam trap

The AWS exam often tests the principle that an explicit Deny overrides any Allow, and candidates mistakenly focus on the Allow statement's permissions (like missing ListBucket) instead of recognizing that the Deny statement with a condition is the root cause of the 'AccessDenied' error.

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 Deny statement with the condition explicitly denies access to the 'confidential' prefix for accounts other than 123456789012.

The Deny statement explicitly denies access to the 'confidential' prefix when the request comes from an AWS account other than 123456789012. Since the data engineering team's role likely belongs to a different account, the Deny condition matches and overrides any Allow statements, resulting in an 'AccessDenied' error. In IAM, an explicit Deny always takes precedence over an Allow, so even if the Allow statement grants PutObject, the Deny blocks the upload.

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 condition in the Deny statement requires the team to use a specific source IP address.
Why it's wrong here
The condition uses aws:PrincipalAccount, not source IP.
✗
The Allow statement only grants GetObject and PutObject, but the team needs ListBucket.
Why it's wrong here
The error is AccessDenied for PutObject, which is allowed in the Allow statement, but the Deny overrides it.
✓
The Deny statement with the condition explicitly denies access to the 'confidential' prefix for accounts other than 123456789012.
Why this is correct
The Deny statement applies to all actions on the confidential prefix for accounts not matching 123456789012, overriding the Allow.
✗
The Allow statement's resource does not include the 'confidential' prefix.
Why it's wrong here
The Allow statement includes all objects under my-data-lake, including confidential, but the Deny overrides.

Go deeper

MLS-C01 Data Engineering Practice Question

Exhibit

Why each option matters

Option-by-option breakdown

Related to this question