The answer is that the measures are using row context instead of filter context, causing them to evaluate over the entire Sales table regardless of the year grouping in SUMMARIZECOLUMNS. This happens because SUMMARIZECOLUMNS provides row context only for the columns listed in its grouping parameters, but measures like [Total Sales] and [Total Cost] that rely on SUMX with a row iterator do not automatically inherit filter context from the year column. As a result, the profit margin calculation repeats the same total for every year, ignoring the varying sales amounts. On the Microsoft Power BI Data Analyst PL-300 exam, this tests your understanding of context transition and how SUMMARIZECOLUMNS differs from SUMMARIZE or CALCULATE—a common trap is assuming row context from grouping columns will filter table iterators. To fix this, wrap the SUMX in a CALCULATE to force context transition, or use SUM after filtering. Memory tip: row context is a row-by-row loop; filter context is a sieve—SUMMARIZECOLUMNS only hands you the sieve for grouped columns, not for the whole table.
PL-300 Visualize and analyze the data Practice Question
This PL-300 practice question tests your understanding of visualize and analyze 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.
You run the above DAX query in DAX Studio. The result shows profit margin values for each year, but all values are the same for every year despite sales amounts varying. 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.
The Sales table contains a calculated column that overrides the year filter.
Why wrong: Calculated columns could cause issues, but the problem is with measures not respecting filter context.
B
The DIVIDE function is not handling division by zero correctly.
Why wrong: Division by zero would cause blanks, not constant values.
C
The SUMMARIZECOLUMNS function is not compatible with measures that use SUMX.
Why wrong: SUMMARIZECOLUMNS works with measures; the issue is filter propagation.
D
The measures use row context instead of filter context, causing them to evaluate over the entire table.
SUMMARIZECOLUMNS provides filter context, but the SUMX iterates over the Sales table without considering the current year filter because the measures are not using CALCULATE to transform row context.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The measures use row context instead of filter context, causing them to evaluate over the entire table.
The issue is that the measures [Total Sales] and [Total Cost] are defined using SUMX over the entire Sales table without any filter context propagation from SUMMARIZECOLUMNS. The SUMMARIZECOLUMNS function only provides row context for the columns in the group by, but measures that use SUMX with a row iterator (Sales table) are not automatically filtered by the year. To get year-level profit margin, the measures should be written using CALCULATE with appropriate filters, or the SUMX should be replaced with SUM after filtering. Option C is correct because the measures are not respecting the filter context. Option A is incorrect because there is no calculated column. Option B is incorrect because row context is not an issue; it's filter context. Option D is incorrect because error handling is not the cause.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 Sales table contains a calculated column that overrides the year filter.
Why it's wrong here
Calculated columns could cause issues, but the problem is with measures not respecting filter context.
✗
The DIVIDE function is not handling division by zero correctly.
Why it's wrong here
Division by zero would cause blanks, not constant values.
✗
The SUMMARIZECOLUMNS function is not compatible with measures that use SUMX.
Why it's wrong here
SUMMARIZECOLUMNS works with measures; the issue is filter propagation.
✓
The measures use row context instead of filter context, causing them to evaluate over the entire table.
Why this is correct
SUMMARIZECOLUMNS provides filter context, but the SUMX iterates over the Sales table without considering the current year filter because the measures are not using CALCULATE to transform row context.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PL-300 NAT questions on configuration and troubleshooting.
Visualize and analyze the data — This question tests Visualize and analyze the data — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The measures use row context instead of filter context, causing them to evaluate over the entire table. — The issue is that the measures [Total Sales] and [Total Cost] are defined using SUMX over the entire Sales table without any filter context propagation from SUMMARIZECOLUMNS. The SUMMARIZECOLUMNS function only provides row context for the columns in the group by, but measures that use SUMX with a row iterator (Sales table) are not automatically filtered by the year. To get year-level profit margin, the measures should be written using CALCULATE with appropriate filters, or the SUMX should be replaced with SUM after filtering. Option C is correct because the measures are not respecting the filter context. Option A is incorrect because there is no calculated column. Option B is incorrect because row context is not an issue; it's filter context. Option D is incorrect because error handling is not the cause.
What should I do if I get this PL-300 question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PL-300 NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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