Quick Answer
The answer is an invalid or expired authentication token, as a REST API 401 unauthorized error directly signals that the server could not verify the client’s identity. When a script targeting a Cisco Nexus 9000 switch fails with this status code, it means the request either lacks proper credentials or the provided token—often obtained via HTTP Basic Auth—has expired or been rejected. On the Cisco DCCOR / CCNP Data Center Core 350-601 exam, this scenario tests your understanding of REST API security for Nexus platforms, where token-based authentication is mandatory for automation scripts. A common trap is confusing a 401 error with a 403 Forbidden; remember that 401 means “who are you?” (missing or bad credentials), while 403 means “you’re known but not allowed.” For a quick memory tip: think “401 = Identity crisis, 403 = Permission denied.”
This 350-601 practice question tests your understanding of automation. 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.
A data center team is troubleshooting an automation script that uses REST API to configure a Cisco Nexus 9000 switch. The script fails with a '401 Unauthorized' 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.
API rate limiting has been exceeded
Why wrong: Rate limiting returns 429 Too Many Requests.
Network connectivity issue between the script and the switch
Why wrong: Connectivity issues would result in timeouts or connection refused errors.
The user account does not have admin privileges
Why wrong: Insufficient privileges would return 403 Forbidden.
Invalid or expired authentication token
401 Unauthorized indicates authentication failure.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Invalid or expired authentication token
A 401 Unauthorized error in REST API communication indicates that the request lacks valid authentication credentials. For Cisco Nexus 9000 switches, REST API access typically requires a token-based authentication (e.g., using HTTP Basic Auth to obtain a session token or cookie). If the token is invalid or expired, the API server rejects the request with a 401 status code, as the script cannot prove its identity.
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.
API rate limiting has been exceeded
Why it's wrong here
Rate limiting returns 429 Too Many Requests.
Network connectivity issue between the script and the switch
Why it's wrong here
Connectivity issues would result in timeouts or connection refused errors.
The user account does not have admin privileges
Why it's wrong here
Insufficient privileges would return 403 Forbidden.
Invalid or expired authentication token
Why this is correct
401 Unauthorized indicates authentication failure.
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.
Common exam traps
Cisco often tests the distinction between 401 Unauthorized (authentication failure) and 403 Forbidden (authorization failure), and candidates mistakenly choose 'insufficient privileges' (Option C) because they confuse authentication with authorization.
Detailed technical explanation
The Nexus 9000 REST API uses HTTP Basic Authentication to generate a session token (stored in a cookie) or requires the token in the Authorization header for subsequent requests. Tokens have a configurable timeout (default 600 seconds) and must be refreshed. A common real-world scenario is a script that obtains a token once but runs longer than the token's lifetime, causing subsequent API calls to fail with 401.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A junior network technician can log in to a core router but cannot reach the enable prompt or configuration mode. The AAA server is authenticating the login — but the authorisation policy only grants privilege level 1, not 15. Authentication (who you are) is working; authorisation (what you can do) is not.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Automation — study guide chapter
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Automation practice questions
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All 350-601 questions
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Cisco DCCOR / CCNP Data Center Core 350-601 study guide
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350-601 practice test guide
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FAQ
Automation — This question tests Automation — Read the scenario before looking for a memorised answer..
The correct answer is: Invalid or expired authentication token — A 401 Unauthorized error in REST API communication indicates that the request lacks valid authentication credentials. For Cisco Nexus 9000 switches, REST API access typically requires a token-based authentication (e.g., using HTTP Basic Auth to obtain a session token or cookie). If the token is invalid or expired, the API server rejects the request with a 401 status code, as the script cannot prove its identity.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This 350-601 practice question is part of Courseiva's free Cisco 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 350-601 exam.
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