- A
The data being transferred is skewed, causing the sink to be overwhelmed.
Why wrong: Data skew affects processing performance, not the ability to establish a TCP connection to the database.
- B
The corporate firewall or network device is closing idle TCP connections to the SQL Server database.
Firewalls often drop idle connections after a timeout period. When the pipeline uses a connection from the pool that has been idle, the connection is no longer valid, causing a timeout. This explains the intermittent nature.
- C
The SQL Server database is experiencing high CPU utilization during the pipeline execution window.
Why wrong: High CPU would cause slow queries or timeouts but would not produce a TCP connection timeout error; the error is about establishing a connection, not executing queries.
- D
The self-hosted integration runtime is running out of memory during peak loads.
Why wrong: Memory exhaustion would typically result in 'out of memory' errors or slow performance, not TCP connection timeouts.
Quick Answer
The answer is that the corporate firewall or network device is closing idle TCP connections to the SQL Server database. This is the most likely cause of the intermittent Azure Data Factory self-hosted IR connection timeout because the sporadic nature of the error, combined with the fact that SSMS works from the same VM, points to a network intermediary dropping long-idle TCP sessions. ADF pipelines can hold connections open between activities or during extended data transfers, and if no keep-alive packets are sent within the firewall’s idle timeout window—commonly 4 to 30 minutes—the firewall silently kills the socket. When the self-hosted IR tries to reuse that stale connection, it fails with a timeout. On the DP-203 exam, this scenario tests your understanding of how network intermediaries interact with ADF’s connection pooling, and a common trap is to blame the SHIR or SQL Server configuration when the real culprit is a firewall’s idle timeout. Remember the memory tip: “Idle firewall, timed-out wire.”
DP-203 Design and develop data processing Practice Question
This DP-203 practice question tests your understanding of design and develop data processing. 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.
You are a data engineer at a healthcare analytics company. The company uses Azure Data Factory (ADF) to orchestrate data pipelines that ingest patient data from on-premises SQL Server databases into Azure Synapse Analytics. Recently, the pipeline has been failing intermittently with the following error: 'Failure happened on 'Sink' side. ErrorCode=SqlFailedToConnect, Type=Microsoft.DataTransfer.Common.Shared.HybridDeliveryException, Message=Cannot connect to SQL Server Database. The TCP connection to the host <server_name>, port 1433 has failed. Error: 'Connection timed out.'.' The on-premises SQL Server is behind a corporate firewall. The ADF self-hosted integration runtime (SHIR) is installed on a VM inside the corporate network. You have verified that the SHIR is running and that the SQL Server is accessible from the SHIR VM using SQL Server Management Studio (SSMS). The error occurs sporadically, not consistently. What is the most likely cause of the intermittent connection timeout?
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
The corporate firewall or network device is closing idle TCP connections to the SQL Server database.
The intermittent nature of the timeout, combined with the fact that the SHIR VM can connect to SQL Server via SSMS, strongly suggests that the corporate firewall or a network intermediary (such as a load balancer or NAT device) is closing idle TCP connections. ADF pipelines may hold connections open between activities or during long-running data transfers, and if no keep-alive packets are sent within the firewall's idle timeout window (commonly 4–30 minutes), the firewall drops the TCP session. When ADF attempts to reuse that connection, it receives a 'Connection timed out' error because the socket is no longer valid.
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 data being transferred is skewed, causing the sink to be overwhelmed.
Why it's wrong here
Data skew affects processing performance, not the ability to establish a TCP connection to the database.
- ✓
The corporate firewall or network device is closing idle TCP connections to the SQL Server database.
Why this is correct
Firewalls often drop idle connections after a timeout period. When the pipeline uses a connection from the pool that has been idle, the connection is no longer valid, causing a timeout. This explains the intermittent nature.
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 SQL Server database is experiencing high CPU utilization during the pipeline execution window.
Why it's wrong here
High CPU would cause slow queries or timeouts but would not produce a TCP connection timeout error; the error is about establishing a connection, not executing queries.
- ✗
The self-hosted integration runtime is running out of memory during peak loads.
Why it's wrong here
Memory exhaustion would typically result in 'out of memory' errors or slow performance, not TCP connection timeouts.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates assume the error is due to resource exhaustion (CPU, memory, or data skew) because those are common causes of intermittent failures, but the specific 'Connection timed out' error points to a network-layer issue, not a server-side performance bottleneck.
Detailed technical explanation
How to think about this question
TCP keep-alive is governed by RFC 1122, and many firewalls have a default idle timeout of 300 seconds (5 minutes) for established connections. ADF's SHIR uses ADO.NET connections to SQL Server, which by default do not enable keep-alive; the connection pool may hold a socket open longer than the firewall's timeout. In a healthcare analytics scenario with large patient data loads, a pipeline may pause between copy activities or during staging, causing the firewall to terminate the TCP session. Enabling SQL Server's 'Keep Alive' setting in the connection string (e.g., 'Keep Alive=30000') can mitigate this.
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.
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
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 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.
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FAQ
Questions learners often ask
What does this DP-203 question test?
Design and develop data processing — This question tests Design and develop data processing — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The corporate firewall or network device is closing idle TCP connections to the SQL Server database. — The intermittent nature of the timeout, combined with the fact that the SHIR VM can connect to SQL Server via SSMS, strongly suggests that the corporate firewall or a network intermediary (such as a load balancer or NAT device) is closing idle TCP connections. ADF pipelines may hold connections open between activities or during long-running data transfers, and if no keep-alive packets are sent within the firewall's idle timeout window (commonly 4–30 minutes), the firewall drops the TCP session. When ADF attempts to reuse that connection, it receives a 'Connection timed out' error because the socket is no longer valid.
What should I do if I get this DP-203 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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Last reviewed: Jun 11, 2026
This DP-203 practice question is part of Courseiva's free Microsoft 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 DP-203 exam.
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