This PCEP practice question tests your understanding of data types, variables, basic i/o and operators. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Refer to the exhibit.
JSON policy:
{
"policy": "allow",
"ports": [80, 443]
}A Python script reads this JSON and needs to check if port 8080 is allowed. Which expression correctly checks? Assume data is already parsed into a dictionary.
Refer to the exhibit.
JSON policy:
{
"policy": "allow",
"ports": [80, 443]
}data["ports"].contains(8080)
Why wrong: Lists do not have a .contains() method.
data.get("ports") == 8080
Why wrong: Compares list to integer, always False.
8080 in data["ports"]
Correct; checks if 8080 is in the list.
"ports" in data
Why wrong: Checks if key exists, not port value.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
8080 in data["ports"]
Option C is correct because the `in` operator checks for membership in a list. Since `data["ports"]` is a list (e.g., `[80, 443, 8080]`), `8080 in data["ports"]` returns `True` if 8080 is present. This directly tests whether port 8080 is allowed.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
data["ports"].contains(8080)
Why it's wrong here
Lists do not have a .contains() method.
data.get("ports") == 8080
Why it's wrong here
Compares list to integer, always False.
8080 in data["ports"]
Why this is correct
Correct; checks if 8080 is in the list.
Related concept
Read the scenario before looking for a memorised answer.
"ports" in data
Why it's wrong here
Checks if key exists, not port value.
Common exam traps
Python Institute often tests the distinction between checking for a key in a dictionary (`key in dict`) versus checking for a value in a list (`value in list`), and candidates mistakenly use `contains()` (from Java or other languages) or confuse dictionary key existence with list membership.
Detailed technical explanation
The `in` operator in Python calls the `__contains__` method of the object, which for lists performs a linear search (O(n) time complexity). For large lists, this could be inefficient; a `set` would offer O(1) average lookup. In real-world scenarios, such as firewall rule validation, using `in` on a list is straightforward but may need optimization for high-frequency checks.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the PCEP exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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FAQ
Data Types, Variables, Basic I/O and Operators — This question tests Data Types, Variables, Basic I/O and Operators — Read the scenario before looking for a memorised answer..
The correct answer is: 8080 in data["ports"] — Option C is correct because the `in` operator checks for membership in a list. Since `data["ports"]` is a list (e.g., `[80, 443, 8080]`), `8080 in data["ports"]` returns `True` if 8080 is present. This directly tests whether port 8080 is allowed.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 30, 2026
This PCEP practice question is part of Courseiva's free Python Institute certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCEP exam.
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