The correct answer is that the Date table does not contain all dates from the previous year. SAMEPERIODLASTYEAR works by shifting the current filter context exactly one year back, but it requires a contiguous, continuous date table to map those dates; if any dates from the previous year are missing from the Date table, the function cannot find a matching range and returns blank. On the PL-300 exam, this tests your understanding of time intelligence prerequisites—specifically that date tables must be marked as such, have no gaps, and span the entire period needed for calculations. A common trap is assuming the measure logic is flawed or that DIVIDE is causing the blank, but the root cause is almost always an incomplete date dimension. Memory tip: think of SAMEPERIODLASTYEAR as a bridge—if the bridge has missing planks (missing dates), you cannot cross to the previous year, so you get nothing.
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.
Exhibit
Refer to the exhibit.
```dax
Sales YoY % =
VAR CurrentSales = SUM(Sales[Amount])
VAR PreviousSales = CALCULATE(SUM(Sales[Amount]), SAMEPERIODLASTYEAR('Date'[Date]))
RETURN
DIVIDE(CurrentSales - PreviousSales, PreviousSales)
```
You have the DAX measure shown. The measure returns blank for some periods even though there are sales in the current period. 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.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The Date table does not contain all dates from the previous year.
Option B is correct because SAMEPERIODLASTYEAR requires a contiguous date table to work correctly; if dates are missing, it returns blank. Option A is wrong because the measure does not have filter context issues by default. Option C is wrong because DIVIDE handles division by zero and returns blank, but the issue is that PreviousSales is blank. Option D is wrong because the measure is not using a variable incorrectly.
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 Date table does not contain all dates from the previous year.
Why this is correct
SAMEPERIODLASTYEAR requires a full date range.
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.
✗
The measure is not properly filtered by the current context.
Why it's wrong here
Filter context is inherited from the report.
✗
The variable CurrentSales is not evaluated correctly.
Why it's wrong here
CurrentSales should evaluate fine.
✗
The DIVIDE function returns blank when denominator is zero.
Why it's wrong here
Denominator being zero would cause blank, but numerator exists.
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 cloud solutions architect for a retail company is evaluating services for a new workload. The correct answer here reflects best practice for the specific scenario described — not a general cloud recommendation. NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated. Cloud exam questions reward reading the constraint carefully: the same technology can be right or wrong depending on the use case.
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 Date table does not contain all dates from the previous year. — Option B is correct because SAMEPERIODLASTYEAR requires a contiguous date table to work correctly; if dates are missing, it returns blank. Option A is wrong because the measure does not have filter context issues by default. Option C is wrong because DIVIDE handles division by zero and returns blank, but the issue is that PreviousSales is blank. Option D is wrong because the measure is not using a variable incorrectly.
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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