The answer is to increase the frequency of transaction log backups on the source database. This is correct because during an online migration via Azure Database Migration Service, DMS continuously captures and applies ongoing log changes from the source to the target Azure SQL Managed Instance. With limited network bandwidth of 100 Mbps, the migration takes longer, allowing the transaction log to grow unchecked; more frequent log backups truncate the inactive portion of the log, preventing log space exhaustion and keeping the log file manageable. On the DP-300 exam, this scenario tests your understanding of how online migration interacts with log chain management—a common trap is to focus on scaling the target instance or pausing the migration, but the real bottleneck is the source log growth. Remember the key principle: online migration is log-driven, so controlling log size on the source is your primary lever. A helpful memory tip is “Backup often, log stays soft”—frequent backups keep the log from hardening into a failure risk.
DP-300 Plan and implement data platform resources Practice Question
This DP-300 practice question tests your understanding of plan and implement data platform resources. 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 the database administrator for a large e-commerce company. The company has a SQL Server 2019 Enterprise Edition instance running on-premises with multiple databases. One of the databases, 'OrdersDB', is 2 TB in size and has a high transaction rate. The company plans to migrate 'OrdersDB' to Azure SQL Managed Instance to reduce operational overhead. The migration must have minimal downtime, and the target service tier must be Business Critical with 16 vCores. You have set up a test environment and performed a successful test migration using the Azure Database Migration Service (DMS) with online mode. During the final migration, the network bandwidth between on-premises and Azure is limited to 100 Mbps. The migration is taking longer than expected, and you are concerned about the log backup growth. What should you do to minimize the risk of the migration failing due to log space exhaustion?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "minimum / minimize"
Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Increase the frequency of transaction log backups on the source database to keep the log small.
Option D is correct because increasing the frequency of transaction log backups on the source database reduces the size of the active log, preventing log space exhaustion during the long-running online migration. The Azure Database Migration Service (DMS) in online mode continuously captures and applies log changes, so a smaller log reduces the risk of the log file filling up before backups can be taken, especially under constrained network bandwidth.
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.
✗
Switch to offline migration mode to avoid log growth issues.
Why it's wrong here
Offline migration requires downtime and may not meet the minimal downtime requirement.
✗
Pause the migration and request a higher network bandwidth from the ISP.
Why it's wrong here
This may cause delays and is not under your control.
✗
Reduce the Azure SQL Managed Instance storage performance tier to standard to reduce cost.
Why it's wrong here
Storage tier does not affect log backup growth on the source.
✓
Increase the frequency of transaction log backups on the source database to keep the log small.
Why this is correct
Frequent log backups prevent log file from growing too large during migration.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates may think offline migration is the only way to avoid log growth, but the question explicitly requires minimal downtime, making online mode mandatory, and the correct solution is to manage the log backup frequency rather than changing the migration mode or bandwidth.
Detailed technical explanation
How to think about this question
In online DMS migrations, the service uses the transaction log to capture ongoing changes after the initial full data load. The log backup frequency on the source directly controls how often the log is truncated (via CHECKPOINT and log backup). With 100 Mbps bandwidth, the log shipping rate may lag behind the transaction rate, causing the log to grow. Increasing log backup frequency (e.g., to every 5 minutes) ensures the log is truncated more often, preventing it from filling the disk. Additionally, SQL Server's log management relies on VLF (Virtual Log File) truncation, which only occurs after a log backup, so frequent backups are critical.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this DP-300 question in full detail.
Plan and implement data platform resources — This question tests Plan and implement data platform resources — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Increase the frequency of transaction log backups on the source database to keep the log small. — Option D is correct because increasing the frequency of transaction log backups on the source database reduces the size of the active log, preventing log space exhaustion during the long-running online migration. The Azure Database Migration Service (DMS) in online mode continuously captures and applies log changes, so a smaller log reduces the risk of the log file filling up before backups can be taken, especially under constrained network bandwidth.
What should I do if I get this DP-300 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: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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