MockRounds Logo

PowerBI Advanced Developer Interview Challenge: Deep-Dive MCQ Practice Quiz

  1. Question 1

    In Power BI, what is a key disadvantage of using Import mode with large datasets, and what is the maximum dataset size limit in Import mode (excluding Premium capacity)?

    1. A. Slow refresh rates; 1 GB per dataset
    2. B. Cannot use DAX; 100 MB per dataset
    3. C. No incremental refresh; 10 GB per report
    4. D. Realtime data unavailability; 1 TB per table
    5. E. Supports only numeric data; 500 MB per model

  2. Question 2

    Scenario: You created a Power BI report in development and now want to deploy it to UAT (User Acceptance Testing) before production. What is a best practice for switching environments, especially with different data sources?

    1. A. Manually edit queries for each environment in Power Query
    2. B. Use dynamic data source parameters and modify their values upon deployment
    3. C. Split the Power BI file into separate files per environment
    4. D. Duplicate reports for each environment and update visuals
    5. E. Create new DirectQuery connections for UAT

  3. Question 3

    Which technique should you prioritize to address performance issues caused by many-to-many relationships between tables in a Power BI model?

    1. A. Add index columns to both tables
    2. B. Use a bridging (intermediate) table to resolve ambiguity
    3. C. Set both tables to a single direction filter
    4. D. Merge the tables into a single flat structure
    5. E. Change relationship type from many-to-many to one-to-one

  4. Question 4

    You need to create a calculated column based on multiple complex conditions in Power BI. Which feature in Power Query best supports this requirement?

    1. A. Merge Queries using Left Join
    2. B. Custom Column with M language
    3. C. DirectQuery advanced editor
    4. D. Data profiling
    5. E. Conditional Formatting

  5. Question 5

    Given a Power BI model with millions of rows in a single table causing slow report performance, which action most directly improves performance for only that table?

    1. A. Enable Row-Level Security
    2. B. Swap import mode for DirectQuery mode
    3. C. Reduce column cardinality and remove unnecessary columns
    4. D. Add calculated measures for faster DAX calculations
    5. E. Use star schema for the entire model

  6. Question 6

    Which DAX concept can cause a circular dependency error while authoring calculated columns?

    1. A. Referencing the same column you are defining within its own formula
    2. B. Using CALCULATE without any filter argument
    3. C. Aggregating numeric columns with SUMX
    4. D. Referencing unrelated tables
    5. E. Creating duplicate measures

  7. Question 7

    What does Row-Level Security (RLS) achieve in Power BI, and how is it typically implemented?

    1. A. Protects table schema; controlled via deployment pipelines
    2. B. Restricts visual access; applied through dashboard settings
    3. C. Filters data per user; defined via roles and DAX filter expressions
    4. D. Encrypts data-in-transit; set up using gateway settings
    5. E. Allows only admins to edit reports; managed in Power Query

  8. Question 8

    Scenario: You need to calculate Month-over-Month growth for sales in Power BI using DAX. Which formula correctly computes this?

    1. A. (SUM(Sales) / PREVIOUSMONTH(Sales)) - 1
    2. B. ([Sales] - CALCULATE([Sales], PREVIOUSMONTH('Date'[Date]))) / CALCULATE([Sales], PREVIOUSMONTH('Date'[Date]))
    3. C. ([Sales] + LASTMONTH([Sales])) / [Sales]
    4. D. SUM([Sales]) - LASTDATE([Sales])
    5. E. ([Sales] - NEXTMONTH([Sales])) / [Sales]

  9. Question 9

    You have a report that runs slowly due to complex data models. Which optimization step should be prioritized for improved Power BI performance?

    1. A. Add more calculated columns
    2. B. Remove unnecessary relationships and enforce star schema design
    3. C. Convert all tables to text format
    4. D. Duplicate queries for each visual
    5. E. Use only slicers on visuals

  10. Question 10

    In Power Query, when should you use the Append operation versus the Merge operation? Provide an example scenario.

    1. A. Append is for adding new columns, Merge is for new rows
    2. B. Append combines tables vertically (e.g., Q1 and Q2 sales data together), while Merge combines tables horizontally based on a key (e.g., joining sales with customer info)
    3. C. Append removes duplicates, Merge removes nulls
    4. D. Append sorts tables, Merge filters tables
    5. E. Append is for static data, Merge is for live data

  11. Question 11

    You want to ensure data refreshed in Power BI only loads newly added records each time. What is the recommended approach?

    1. A. Use incremental refresh policies specifying rangeStart and rangeEnd parameters
    2. B. Filter the visuals to show only newest data
    3. C. Set up page level security
    4. D. Re-upload all source files each time
    5. E. Duplicate queries with updated source paths

  12. Question 12

    In SQL, what is the main difference between the LEAD and LAG window functions?

    1. A. LEAD gets previous row, LAG gets next row
    2. B. LEAD retrieves a subsequent row relative to the current row, LAG retrieves a preceding row
    3. C. LEAD aggregates data, LAG calculates running totals
    4. D. LEAD sorts data ascending, LAG sorts descending
    5. E. LEAD only usable in SELECT, LAG only in WHERE

  13. Question 13

    A query contains: SELECT ID, SUM(sales) FROM table WHERE SUM(sales) u003E 10000. What is the error with this SQL statement?

    1. A. SUM can only be used with numeric columns, not in WHERE
    2. B. SUM should be replaced with COUNT
    3. C. Aggregate functions are not allowed in SELECT
    4. D. Aggregate functions like SUM must be used in the HAVING clause instead of WHERE
    5. E. SQL does not support SUM

  14. Question 14

    What is the correct sequence for query execution in standard SQL?

    1. A. SELECT, FROM, WHERE, GROUP BY, ORDER BY
    2. B. FROM, WHERE, GROUP BY, HAVING, SELECT, ORDER BY
    3. C. WHERE, FROM, SELECT, HAVING, ORDER BY
    4. D. GROUP BY, SELECT, WHERE, ORDER BY, HAVING
    5. E. SELECT, HAVING, FROM, ORDER BY, WHERE

  15. Question 15

    Which method best implements report-level security to restrict user access to certain visualizations in Power BI?

    1. A. Hide visuals in the Power Query editor
    2. B. Use the Manage Permissions feature to assign users to specific report roles
    3. C. Assign read-only access in the data source
    4. D. Apply Row-Level Security and manage user-role mapping in the Power BI service
    5. E. Disable refresh for restricted pages
mockrounds.com Learn • Practice • Evaluate