Microsoft Power BI Interview Questions and Answers 2026

1. What do you mean by Power BI?

Using Power BI, data can be connected from various sources, converted to interactive reports, and displayed on dashboards. Microsoft business analytics services enable data modeling, visualization, and reporting, thus making this platform a one-stop solution for ad-hoc decision-making.

2. What were the main components of Power BI?

Power BI components are the main ones as follows:

• Power BI Desktop: An application where reports are made.

• Power BI Service (Cloud): Online SaaS service where sharing and collaboration of reports takes place.

• Power BI Mobile: Apps through which users get access to view reports on mobile devices.

• Power BI Gateway: Connecting on-premise data to Power BI Services.

• Power BI Report Server: Host reports on-premise.

• Power BI Embedded: Reports for other applications embedded inside other applications.

3. What is DAX in Power BI?

DAX (Data Analysis Expressions) is a formula language that can be used by Power BI, Power Pivot, and SSAS to calculate custom columns, measures, and custom tables. It contains functions for filtering and aggregating data, for example: CALCULATE, FILTER, SUMX, etc.

4. Explain the difference between a Measure and a Calculated Column.

• Calculated Column: Computed during data load on the model row-by-row basis for calculations.

• Measure: On-the-fly calculations based on the user interaction and applied filters. Measures take no space at the time of storage.

Example:
Total Sales = SUM(Sales[Amount]) (Measure)
Profit = Sales[Amount] - Sales[Cost] (Calculated Column)

5. Different types of data connectivity modes in Power BI?

There are different types of modes available in Power BI for data connectivity:

1. Import Mode – imports data into Power BI and stores it locally.

2. Direct Query – works in real-time by reading and querying data from the source.

3. Live Connection – connects to the existing Analysis Services model.

4. Composite Mode – combines Import and Direct Query Modes.

6. What is Power Query and how does it work?

Power Query is the tool through which data in Power BI is transformed by the user—extracting, cleansing, and reshaping it before placing it into the model. It uses the M language for filtering, merging, and grouping when cleaning data together.

7. What are relations in Power BI?

A relationship links two tables in a Power BI model (the primary and foreign keys) and specifies how data from different tables relate to one another, allowing analysis across tables.

Types:

1. One-to-Many (most common)

2. One-to-One

3. Many-to-Many

8. What are Filters and Slicers in Power BI?

• Filters: Limit data in a visual, page, or report.

• Slicers: Visual controls that allow an interactive filter on a field (for example, by date, category, or region).

9. What is the use of Power BI Gateway?

The Power BI Gateway acts as a bridge between an organization’s local data and the Power BI cloud service. It allows scheduling data refreshes or establishing live connections to SQL Server, Oracle, or other local databases.

10. Describe the demarcation of Power BI Pro, Power BI Premium, and Power BI Free.

• Power BI Free: For personal use only; reports cannot be shared.

• Power BI Pro: Enables collaboration and sharing of reports.

• Power BI Premium: Provides dedicated cloud capacity, supports large datasets, and allows on-premise hosting via Report Server.

11. Explain Row-Level Security (RLS) in Power BI.

RLS restricts access to data for specific users based on filters defined in roles. For example, a sales representative can only view data for their assigned region. RLS can be implemented using DAX filters or Azure Active Directory groups.

12. What is Power BI Dataflow?

A Dataflow is a collection of transformations (using Power Query) stored in Power BI Service to create reusable data preparation pipelines across reports for enhanced data consistency and governance.

13. What are the Common Sources of Data in Power BI?

Power BI can connect to numerous sources, including:

• SQL Server, MySQL, Oracle

• Excel, CSV, SharePoint

• Azure, Google Big Query, Snowflake

• Web APIs and online services like Salesforce and Dynamics 365

14. What are Bookmarks in Power BI?

Bookmarks capture the current state of a report page—including filters, visuals, and layout—so users can easily return to it. They are typically used for storytelling and navigation within dashboards.

15. What are Tooltips in Power BI?

Tooltips are pop-ups that appear when hovering over a data point to provide additional insights or context without cluttering the main report.

16. Explain Drill-through and Drill-down in Power BI.

• Drill Down: Allows users to navigate through a data hierarchy (e.g., Year → Quarter → Month).

• Drill Through: Links users to a detailed report page for a specific data point (e.g., clicking on a region to view its sales details).

17. How do you optimize performance in Power BI reports?

• Use Import mode when possible.

• Avoid excessive calculated columns.

• Use aggregations and summarized tables.

• Minimize visuals on a page.

• Enable query reduction and incremental refresh.

18. What is Incremental Refresh in Power BI?

Incremental Refresh allows large datasets to refresh only new or changed data instead of reloading the entire dataset. This improves performance and reduces refresh time.

19. How do you publish and share Power BI reports?

Reports can be published from Power BI Desktop to the Power BI Service using a Power BI Pro or Premium license. Once published, you can:

• Share dashboards

• Create workspaces

• Embed reports in websites or applications

20. What are KPIs in Power BI?

A KPI (Key Performance Indicator) visual compares actual values to target metrics, showing performance through color indicators or trend icons. It helps organizations monitor progress toward goals.

Bonus Tip:

To strengthen your Power BI knowledge, practice building dashboards, writing DAX formulas, and connecting to live data sources.

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