- A
The JDBC driver is missing the 'redshift' compatibility mode setting.
Why wrong: The 'redshift' compatibility mode is not a standard requirement for Glue-JDBC connections; the error is not caused by missing this setting.
- B
SSL is not enabled on the Redshift cluster.
Correct. If the Redshift cluster enforces SSL, the connection will be rejected without SSL, causing the 'server closed the connection unexpectedly' error.
- C
The Glue job's security group does not allow outbound traffic to the Redshift cluster.
Why wrong: Security group misconfiguration leads to timeout or 'connection refused', not a server-side close of an established connection.
- D
AWS Glue does not support Redshift as a data source.
Why wrong: AWS Glue natively supports Redshift as a data source via JDBC.
DEA-C01 Redshift JDBC connection Practice Question
This DEA-C01 practice question tests your understanding of data operations and support. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. A key principle to apply: redshift JDBC connection. 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 runs a nightly AWS Glue ETL job that writes results to an Amazon Redshift table using the JDBC connector. Recently, the job has been failing with the error 'ERROR: connection to server at ... failed: server closed the connection unexpectedly'. The Redshift cluster is in a private subnet with a VPC endpoint for S3. The Glue job runs in the same VPC with enhanced VPC routing enabled. Which 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 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
SSL is not enabled on the Redshift cluster.
The error 'server closed the connection unexpectedly' typically indicates that the Redshift cluster rejected the connection, often because SSL is required but not enabled in the Glue JDBC connection. Redshift clusters can be configured with the `require_ssl` parameter set to true, forcing all connections to use SSL. Option B is correct because without SSL, the server terminates the connection. Option A is incorrect because the 'redshift' compatibility mode is not a standard requirement; the JDBC driver works without it. Option C is incorrect because security group issues would cause a timeout or 'connection refused', not a server-side close. Option D is incorrect because Glue supports Redshift as a data source.
Key principle: Redshift JDBC connection
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 JDBC driver is missing the 'redshift' compatibility mode setting.
Why it's wrong here
The 'redshift' compatibility mode is not a standard requirement for Glue-JDBC connections; the error is not caused by missing this setting.
- ✓
SSL is not enabled on the Redshift cluster.
Why this is correct
Correct. If the Redshift cluster enforces SSL, the connection will be rejected without SSL, causing the 'server closed the connection unexpectedly' error.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Redshift JDBC connection
- ✗
The Glue job's security group does not allow outbound traffic to the Redshift cluster.
Why it's wrong here
Security group misconfiguration leads to timeout or 'connection refused', not a server-side close of an established connection.
- ✗
AWS Glue does not support Redshift as a data source.
Why it's wrong here
AWS Glue natively supports Redshift as a data source via JDBC.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Candidates may assume that SSL is optional, but many production Redshift clusters enforce SSL, causing non-SSL connections to be dropped.
Detailed technical explanation
How to think about this question
Treat this as a scenario question. Identify the problem, the constraint, and the best action. Then compare each option against those facts.
KKey Concepts to Remember
- Redshift JDBC connection
- Enhanced VPC routing
TExam Day Tips
- 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
Redshift JDBC connection
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.
Visual reference
Quick reference
AWS S3 Storage Class Comparison
| Storage Class | Min Duration | Retrieval | Use Case |
|---|---|---|---|
| S3 Standard | None | Immediate | Frequently accessed data |
| S3 Standard-IA | 30 days | Immediate | Infrequent access, rapid retrieval |
| S3 One Zone-IA | 30 days | Immediate | Non-critical infrequent data |
| S3 Intelligent-Tiering | None | Immediate–hours | Unknown or changing access patterns |
| S3 Glacier Instant | 90 days | Milliseconds | Archive with instant retrieval |
| S3 Glacier Flexible | 90 days | Minutes–hours | Archive, flexible retrieval |
| S3 Glacier Deep Archive | 180 days | Hours | Long-term compliance archive |
What to study next
Got this wrong? Here's your next step.
Review redshift JDBC connection, then practise related DEA-C01 questions on the same topic to reinforce the concept.
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Data Operations and Support — study guide chapter
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FAQ
Questions learners often ask
What does this DEA-C01 question test?
Data Operations and Support — This question tests Data Operations and Support — Redshift JDBC connection.
What is the correct answer to this question?
The correct answer is: SSL is not enabled on the Redshift cluster. — The error 'server closed the connection unexpectedly' typically indicates that the Redshift cluster rejected the connection, often because SSL is required but not enabled in the Glue JDBC connection. Redshift clusters can be configured with the `require_ssl` parameter set to true, forcing all connections to use SSL. Option B is correct because without SSL, the server terminates the connection. Option A is incorrect because the 'redshift' compatibility mode is not a standard requirement; the JDBC driver works without it. Option C is incorrect because security group issues would cause a timeout or 'connection refused', not a server-side close. Option D is incorrect because Glue supports Redshift as a data source.
What should I do if I get this DEA-C01 question wrong?
Review redshift JDBC connection, then practise related DEA-C01 questions on the same topic to reinforce the concept.
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?
Redshift JDBC connection
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Last reviewed: Jun 20, 2026
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