350-401 REST APIs and Data Models Practice Question
This 350-401 practice question tests your understanding of rest apis and data models. 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.
An engineer is using a Python script to configure a new VLAN on a Cisco Nexus 9000 switch using the NX-API REST API. The script sends a POST request to 'https://switch/api/mo/org.json' with a JSON payload containing the VLAN configuration. The switch responds with a 403 Forbidden 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 user account does not have the required RBAC privileges to configure VLANs.
A 403 Forbidden error indicates that the server understood the request but refuses to authorize it. In NX-API, this often occurs when the user does not have sufficient privileges to perform the operation. The engineer should check that the user account used for authentication has the necessary RBAC roles to configure VLANs.
Key principle: Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
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 payload format is incorrect; the engineer must use XML instead of JSON.
Why it's wrong here
Incorrect because NX-API supports both JSON and XML; format does not cause a 403 error.
✓
The user account does not have the required RBAC privileges to configure VLANs.
Why this is correct
Correct because 403 indicates authorization failure; the user needs appropriate privileges.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Authentication checks who the user is.
✗
The switch does not support NX-API; the engineer must use NETCONF instead.
Why it's wrong here
Incorrect because Nexus 9000 supports NX-API; the error is authorization-related.
✗
The URI is incorrect; the correct URI should be 'https://switch/api/node/mo/org.json'.
Why it's wrong here
Incorrect because the URI '/api/mo/org.json' is correct for NX-API; a wrong URI would result in a 404 error.
Common exam traps
Common exam trap: authentication is not authorization
Logging in proves the user can authenticate. It does not automatically mean the user is allowed to enter privileged or configuration mode. Watch for AAA authorization, privilege level and command authorization details.
Detailed technical explanation
How to think about this question
This kind of question is testing the difference between identity and permission. A user may successfully log in to a router because authentication is working, but still fail to enter configuration mode because authorization is missing, misconfigured or mapped to a lower privilege level.
KKey Concepts to Remember
Authentication checks who the user is.
Authorization controls what the user is allowed to do after login.
Privilege levels affect access to EXEC and configuration commands.
AAA, TACACS+ and RADIUS can separate login success from command access.
TExam Day Tips
→Do not assume successful login means full administrative access.
→Look for words such as cannot enter configuration mode, privilege level, authorization or command access.
→Separate login problems from permission problems before choosing the answer.
Key takeaway
Authentication proves identity; authorization controls what that identity can do after login. Both must work for full privileged access.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-401 questions on access control and AAA configuration.
REST APIs and Data Models — This question tests REST APIs and Data Models — Authentication checks who the user is..
What is the correct answer to this question?
The correct answer is: The user account does not have the required RBAC privileges to configure VLANs. — A 403 Forbidden error indicates that the server understood the request but refuses to authorize it. In NX-API, this often occurs when the user does not have sufficient privileges to perform the operation. The engineer should check that the user account used for authentication has the necessary RBAC roles to configure VLANs.
What should I do if I get this 350-401 question wrong?
Review Cisco AAA concepts — authentication, authorization, and accounting. Study privilege levels (0–15), command authorization under TACACS+, and how RADIUS differs. Then practise related 350-401 questions on access control and AAA configuration.
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?
Authentication checks who the user is.
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