Question 549 of 966

Prepare the data →mediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is a mismatch between the hourly refresh frequency and the daily incremental granularity. This is the most likely cause because Power BI dataflow incremental refresh requires the scheduled refresh interval to align with or be less frequent than the incremental period; attempting an hourly refresh on a 'Day' granularity forces the engine to re-query the entire day’s partition each hour, overwhelming the SharePoint list data source and producing the "not accessible" error. On the PL-300 exam, this scenario tests your understanding of how incremental refresh policies interact with scheduled refresh frequencies—a common trap is to blame the data source credentials or gateway when the real issue is a configuration conflict. Remember the memory tip: "Refresh faster than your partition? You’ll hit the wall." Always ensure your refresh interval respects the incremental window to avoid unnecessary full scans and timeouts.

PL-300 Prepare the data Practice Question

This PL-300 practice question tests your understanding of prepare the data. 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.

Exhibit

Refer to the exhibit.

```json
{
  "workspaceId": "12345678-1234-1234-1234-123456789012",
  "dataflowId": "87654321-4321-4321-4321-210987654321",
  "dataflowName": "SalesDataflow",
  "entities": [
    {
      "name": "Sales",
      "source": "AzureSqlDatabase",
      "refreshPolicy": {
        "type": "Full",
        "interval": "Daily"
      }
    },
    {
      "name": "Product",
      "source": "SharePointList",
      "refreshPolicy": {
        "type": "IncrementalRefresh",
        "interval": "Hourly",
        "incrementalGranularity": "Day"
      }
    }
  ]
}
```

You are examining a Power BI dataflow configuration. The dataflow is scheduled to refresh the 'Sales' entity daily and the 'Product' entity hourly. However, the 'Product' entity refresh fails every hour with an error indicating the SharePoint list data source is not accessible. You need to diagnose the issue. 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.

Question 1mediummultiple choice

Full question →

Exhibit

Refer to the exhibit.

```json
{
  "workspaceId": "12345678-1234-1234-1234-123456789012",
  "dataflowId": "87654321-4321-4321-4321-210987654321",
  "dataflowName": "SalesDataflow",
  "entities": [
    {
      "name": "Sales",
      "source": "AzureSqlDatabase",
      "refreshPolicy": {
        "type": "Full",
        "interval": "Daily"
      }
    },
    {
      "name": "Product",
      "source": "SharePointList",
      "refreshPolicy": {
        "type": "IncrementalRefresh",
        "interval": "Hourly",
        "incrementalGranularity": "Day"
      }
    }
  ]
}
```

A
The refresh interval is too frequent for the incremental granularity of 'Day'
Hourly refresh with daily granularity can cause overlapping partitions and high load.
B
Incremental refresh is not supported for SharePoint list data sources
Why wrong: Power BI supports incremental refresh for SharePoint lists.
C
The workspace ID is missing from the dataflow configuration
Why wrong: The workspace ID is present in the exhibit.
D
The on-premises data gateway is not configured for the SharePoint list
Why wrong: SharePoint Online is a cloud source and does not require a gateway.

Full breakdown with real-world context →

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 refresh interval is too frequent for the incremental granularity of 'Day'

Option A is correct because the 'Product' entity is configured to refresh hourly, but the dataflow's incremental refresh policy is set to a 'Day' granularity. Incremental refresh in Power BI requires the refresh frequency to align with or be less frequent than the incremental period; an hourly refresh on a daily partition causes the engine to attempt to query the entire day's data each time, which can lead to timeouts or errors if the source (SharePoint list) cannot handle the repeated full scans. The error 'data source is not accessible' often masks this underlying mismatch between refresh frequency and incremental granularity.

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 refresh interval is too frequent for the incremental granularity of 'Day'
Why this is correct
Hourly refresh with daily granularity can cause overlapping partitions and high load.
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.
✗
Incremental refresh is not supported for SharePoint list data sources
Why it's wrong here
Power BI supports incremental refresh for SharePoint lists.
✗
The workspace ID is missing from the dataflow configuration
Why it's wrong here
The workspace ID is present in the exhibit.
✗
The on-premises data gateway is not configured for the SharePoint list
Why it's wrong here
SharePoint Online is a cloud source and does not require a gateway.

Common exam traps

Common exam trap: answer the scenario, not the keyword

The trap here is that candidates often assume the error is due to gateway configuration or source incompatibility, but the real issue is a misalignment between the refresh schedule and the incremental refresh granularity, which is a subtle but common configuration mistake in dataflows.

Detailed technical explanation

How to think about this question

In Power BI dataflows, incremental refresh works by partitioning data based on a date/time column and only refreshing the partitions that fall within the defined range (e.g., last 30 days). When the refresh frequency (e.g., hourly) is shorter than the incremental period (e.g., day), the engine may attempt to re-query the entire partition each time, causing excessive load on the source. SharePoint Online lists have API throttling limits (e.g., 300 requests per minute per app principal), and repeated full scans can trigger HTTP 429 or 503 errors, which Power BI may surface as 'data source not accessible'.

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.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

Related PL-300 practice-question pages

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FAQ

Questions learners often ask

What does this PL-300 question test?

Prepare the data — This question tests Prepare the data — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The refresh interval is too frequent for the incremental granularity of 'Day' — Option A is correct because the 'Product' entity is configured to refresh hourly, but the dataflow's incremental refresh policy is set to a 'Day' granularity. Incremental refresh in Power BI requires the refresh frequency to align with or be less frequent than the incremental period; an hourly refresh on a daily partition causes the engine to attempt to query the entire day's data each time, which can lead to timeouts or errors if the source (SharePoint list) cannot handle the repeated full scans. The error 'data source is not accessible' often masks this underlying mismatch between refresh frequency and incremental granularity.

What should I do if I get this PL-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: "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 24, 2026

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