The answer is that the Glue job is not configured to use the same VPC as the Redshift cluster. By default, AWS Glue jobs run in an isolated, serverless environment within a separate VPC managed by AWS, meaning they have no network path to resources in your customer VPC unless you explicitly attach a VPC connection to the job. When you configure a Glue job with a VPC subnet and security group, it places the job’s elastic network interfaces into that VPC, allowing direct communication with Redshift. On the AWS Certified Data Engineer Associate DEA-C01 exam, this scenario tests your understanding that network connectivity failures are almost always a VPC configuration issue, not an authentication or port problem—a common trap is to blame IAM roles or security group rules when the real culprit is the missing VPC attachment. Remember the memory tip: “Glue is homeless by default—give it a VPC address to find Redshift.”
DEA-C01 Data Ingestion and Transformation Practice Question
This DEA-C01 practice question tests your understanding of data ingestion and transformation. 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.
A company is using AWS Glue to run ETL jobs that process data from Amazon S3 and load it into Amazon Redshift. The jobs are failing with the error 'Unable to connect to Redshift cluster'. The Redshift cluster is in the same VPC as the Glue job. What is the MOST likely cause?
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 Glue job is not configured to use the same VPC as the Redshift cluster.
Option A is correct because Glue jobs run in a separate VPC by default, and if the job is not configured to use the same VPC as the Redshift cluster, it cannot connect to it. Option B is incorrect because the Redshift cluster is in the same VPC, so security group rules should allow traffic if properly configured. Option C is incorrect because Redshift port 5439 is the default and should be open. Option D is incorrect because IAM roles are for authentication, not network connectivity.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 Redshift cluster's security group does not allow inbound traffic from the Glue job's security group.
Why it's wrong here
While this could be an issue, the most likely cause is that the Glue job is not in the VPC at all.
✗
The IAM role associated with the Glue job does not have permission to access Redshift.
Why it's wrong here
IAM permissions are necessary but the error message suggests a network connectivity issue.
✓
The Glue job is not configured to use the same VPC as the Redshift cluster.
Why this is correct
Glue jobs need VPC configuration to access resources in a private VPC.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The Redshift cluster is not publicly accessible and Glue is trying to connect from outside the VPC.
Why it's wrong here
If the Glue job is not in the VPC, this is a symptom, not the root cause.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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.
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Data Ingestion and Transformation — This question tests Data Ingestion and Transformation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The Glue job is not configured to use the same VPC as the Redshift cluster. — Option A is correct because Glue jobs run in a separate VPC by default, and if the job is not configured to use the same VPC as the Redshift cluster, it cannot connect to it. Option B is incorrect because the Redshift cluster is in the same VPC, so security group rules should allow traffic if properly configured. Option C is incorrect because Redshift port 5439 is the default and should be open. Option D is incorrect because IAM roles are for authentication, not network connectivity.
What should I do if I get this DEA-C01 question wrong?
Identify which DEA-C01 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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?
Read the scenario before looking for a memorised answer.
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Question Discussion
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