The answer is that the NX-API request was rejected because the command is not permitted through the NX-API interface. This occurs because NX-API enforces a strict allowlist of commands; any command not explicitly allowed—such as certain disruptive show commands or configuration commands that could destabilize the switch—will trigger the “command not allowed” error. This is a deliberate security and stability feature of the NX-API RESTful interface, designed to prevent unauthorized or dangerous operations from being executed via API calls. On the Cisco DCCOR / CCNP Data Center Core 350-601 exam, this concept tests your understanding of NX-API’s role in secure network automation, often appearing in scenario-based questions where a JSON error response is shown. A common trap is assuming the error is due to authentication or syntax, when in fact the command itself is simply not on the allowlist. Remember: if NX-API says “not allowed,” think “not on the list”—the API is a bouncer, not a broken door.
350-601 Automation Practice Question
This 350-601 practice question tests your understanding of automation. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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
{
"error": {
"code": "400",
"message": "Invalid command",
"clierror": "Invalid command at line 1"
}
}
Refer to the exhibit. An NX-API request returns this JSON error. 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 command is not allowed via NX-API
The JSON error indicates that the NX-API request was rejected because the command is not permitted through the NX-API interface. NX-API enforces a strict allowlist of commands; any command not explicitly allowed (e.g., certain show commands or configuration commands that could destabilize the switch) will return this error. This is a security and stability feature of the NX-API RESTful interface.
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.
✗
The API version in the request is mismatched
Why it's wrong here
API version mismatch typically gives a different error code (e.g., 404).
✗
Invalid credentials
Why it's wrong here
Invalid credentials return 401, not 400.
✓
The command is not allowed via NX-API
Why this is correct
Some commands are restricted in NX-API. The error 'Invalid command' suggests a disallowed command.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The switch is in maintenance mode
Why it's wrong here
Maintenance mode would not cause this specific error.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that any CLI command can be executed via NX-API, but in reality, NX-API has a restricted command set, and candidates may incorrectly attribute the error to credentials or API version mismatches.
Detailed technical explanation
How to think about this question
NX-API uses a predefined set of allowed commands defined in the NX-API allowlist, which is enforced by the NX-API process (nxapi) on the switch. Commands like 'show running-config' or 'configure terminal' are typically allowed, but destructive or sensitive commands (e.g., 'reload', 'write erase') are blocked by default. The error is returned as part of the JSON-RPC response with an 'error' key, and the specific code or message indicates the command is not allowed. In production, this prevents accidental or malicious remote execution of critical commands via the API.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
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.
Automation — This question tests Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The command is not allowed via NX-API — The JSON error indicates that the NX-API request was rejected because the command is not permitted through the NX-API interface. NX-API enforces a strict allowlist of commands; any command not explicitly allowed (e.g., certain show commands or configuration commands that could destabilize the switch) will return this error. This is a security and stability feature of the NX-API RESTful interface.
What should I do if I get this 350-601 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
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Question Discussion
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