200-901 Infrastructure and Automation Practice Question
This 200-901 practice question tests your understanding of infrastructure and automation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
A developer is designing a data model for network device configurations using YANG. They need to represent a list of interfaces where each interface has a name (string) and speed (enumeration). Which YANG statement correctly defines this structure?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
list interface { key name; leaf name { type string; } leaf speed { type enumeration; } }
Option C is correct because YANG requires a `list` statement to define a collection of entries with multiple leafs, and a `key` statement to uniquely identify each list entry. The `list interface` with `key name` allows multiple interfaces, each having both a `name` (string) and `speed` (enumeration), matching the requirement exactly.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
leaf interface-list { type string; }
Why it's wrong here
A leaf cannot represent multiple entries; use a list.
✗
leaf-list interface { type string; }
Why it's wrong here
leaf-list is for a single-typed list, cannot group name and speed together.
✓
list interface { key name; leaf name { type string; } leaf speed { type enumeration; } }
Why this is correct
This defines a list with a key, and two leaves for name and speed.
Related concept
Read the scenario before looking for a memorised answer.
✗
list interface { leaf name { type string; } leaf speed { type enumeration; } }
Why it's wrong here
A list must have a key leaf to uniquely identify each entry.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the requirement of the `key` statement in a YANG `list`; candidates may forget that a list without a key is syntactically invalid, leading them to choose option D.
Detailed technical explanation
How to think about this question
In YANG, a `list` represents a collection of data nodes, each containing child leafs, and the `key` statement defines which leaf(s) act as the unique identifier (like a primary key in a database). The `enumeration` type in YANG restricts the `speed` leaf to a predefined set of values (e.g., '10mbps', '100mbps', '1gbps'), ensuring data integrity. This structure is commonly used in NETCONF/RESTCONF models for device configuration, where each interface must be uniquely addressable by its name.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 200-901 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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Infrastructure and Automation — This question tests Infrastructure and Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: list interface { key name; leaf name { type string; } leaf speed { type enumeration; } } — Option C is correct because YANG requires a `list` statement to define a collection of entries with multiple leafs, and a `key` statement to uniquely identify each list entry. The `list interface` with `key name` allows multiple interfaces, each having both a `name` (string) and `speed` (enumeration), matching the requirement exactly.
What should I do if I get this 200-901 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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