Power BI Interview Questions and Answers (2025 Edition)

1. Difference Between a Report and a Dashboard

Report:

  • A report in Power BI is a multi-page, interactive document created in Power BI Desktop.
  • It includes multiple visualizations such as charts, graphs, tables, slicers, and maps.
  • Reports allow deep analytical exploration. Users can interact, filter, and drill down into data.
  • Reports are ideal for detailed data storytelling and insight discovery.

Dashboard:

  • A dashboard is a single-page, interactive canvas in Power BI Service.
  • It shows a snapshot of key KPIs or visuals pinned from different reports or datasets.
  • Dashboards are best for high-level monitoring and quick insights.

Summary: Reports are best for deep analysis, while dashboards provide a quick overview.

2. Types of Power BI Licenses

  1. Power BI Free: For individual use. Limited sharing, no collaboration.
  2. Power BI Pro: Enables sharing and collaboration. Ideal for small teams.
  3. Power BI Premium (Per User – PPU): Includes Pro features + AI capabilities and larger data models.
  4. Power BI Premium (Per Capacity): Organization-wide use. Scalable and robust.

Reason for Licensing: These plans allow flexibility based on scale, collaboration, and performance needs.

3. What is DAX? Difference Between Measures & Calculated Columns

DAX (Data Analysis Expressions) is a formula language for creating custom metrics in Power BI.

Measures:

  • Calculated on-the-fly based on filters/slicers.
  • Used for aggregated values (e.g., SUM, AVERAGE).
  • Example: Total Sales = SUM(Sales[Amount])
  • Efficient in memory usage.

Calculated Columns:

  • Computed when data is loaded or refreshed.
  • Stored in the data model; used like regular columns.
  • Example: FullName = [FirstName] & " " & [LastName]
  • Useful for categorization or row-wise computation.

Reasoning: Measures are dynamic and lightweight. Calculated columns are static and consume memory.

4. SUM vs SUMX, CALCULATE & SUMMARIZE in DAX

SUM:

  • Aggregates a single column.
  • SUM(Sales[Amount])

SUMX:

  • Row-by-row calculation followed by aggregation.
  • SUMX(Sales, Sales[Qty]*Sales[Price])

CALCULATE:

  • Modifies the filter context.
  • CALCULATE(SUM(Sales[Amount]), Sales[Year] = 2024)

SUMMARIZE:

  • Creates summary tables with group-by logic.
  • SUMMARIZE(Sales, Sales[Region], "Total Sales", SUM(Sales[Amount]))

Concept Clarity: Use SUM for simple aggregation; SUMX for row-wise logic. CALCULATE alters context, and SUMMARIZE builds group-level tables.

5. Time Intelligence Functions

Used to analyze time-based data like YTD, MTD, YOY comparisons.

Examples:

  • TOTALYTD(SUM(Sales[Amount]), Dates[Date]): Computes year-to-date total.
  • SAMEPERIODLASTYEAR(Dates[Date]): Compares current with last year’s period.

Reason: Helps create dynamic time-based KPIs and performance analysis.

6. Scheduled Refresh vs Incremental Refresh

Scheduled Refresh:

  • Reloads entire dataset at defined intervals.
  • Useful for small-to-medium datasets.

Incremental Refresh:

  • Only refreshes new or modified data.
  • More efficient for large datasets.
  • Uses partitions and date filters.

Concept Clarity: Scheduled is simpler, but incremental is better for big data performance.

7. What is a Gateway? Types of Power BI Gateways

Gateway connects on-premises data sources to Power BI Service.

  • Personal Gateway: Single user; not shareable; runs on a user’s machine.
  • Standard/Enterprise Gateway: Multiple users; supports various data sources; managed centrally.

Reason: Gateways ensure secure data refresh and real-time access for on-prem data.

8. Direct Query vs Import Mode

Direct Query:

  • Live connection to the source.
  • Real-time updates but may affect performance.

Import Mode:

  • Data imported and stored in Power BI.
  • Faster performance; supports full modeling features.

Concept Clarity: Use Import for performance; DirectQuery for real-time accuracy.

9. What is Row-Level Security (RLS)? Static vs Dynamic RLS

RLS restricts data access for users.

  • Static RLS: Predefined roles with fixed filters.
  • Dynamic RLS: Uses USERNAME() function with security table to filter data at runtime.

Example:

  • Static: Region = “North”
  • Dynamic: Region based on logged-in user in a mapping table.

Reasoning: Dynamic RLS is scalable for larger user bases; static is simple for limited roles.

10. What is a Workspace in Power BI? Roles in Workspace

Workspace: Collaborative environment in Power BI Service.

Roles:

  • Admin: Full control over content and members.
  • Member: Can edit and publish content.
  • Contributor: Build content but can’t manage roles.
  • Viewer: Can only view content.

Use Case: Enables controlled collaboration in teams.

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