200-901 Infrastructure and Automation Practice Question
A large enterprise uses Cisco DNA Center to manage their campus network. They have deployed fabric technology for SD-Access. The network team wants to use the DNA Center REST API to automate the addition of new wireless users to a specific virtual network (VN) based on their location (building). They have identified the API endpoint for creating a user device in the fabric. However, when they send a POST request with the appropriate JSON body, they receive a 400 Bad Request error. The JSON payload includes the mandatory fields for hostname, MAC address, and VN name. What is the most likely cause of the error?
⚠ Common exam trap
Cisco often tests the distinction between HTTP status codes (400 vs 401 vs 403) to see if candidates understand that 400 errors are client-side payload issues, not authentication or authorization problems.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The virtual network name provided does not exist in the fabric.
The 400 Bad Request error indicates that the server cannot process the request due to a client-side issue, such as invalid data in the payload. Since the mandatory fields (hostname, MAC address, VN name) are provided, the most likely cause is that the virtual network (VN) name does not match any existing VN in the fabric. DNA Center validates the VN name against its fabric configuration; if the VN is not defined, the API rejects the request with a 400 error.
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 call requires an authentication token that is missing or expired.
Why it's wrong here
This would result in a 401 Unauthorized error, not 400.
- ✓
The virtual network name provided does not exist in the fabric.
Why this is correct
If the VN doesn't exist, the API returns a 400 error.
- ✗
The MAC address format is incorrect (e.g., lowercase vs uppercase).
Why it's wrong here
DNA Center typically normalizes MAC formats, so this is less likely.
- ✗
The user making the API call does not have sufficient privileges.
Why it's wrong here
Insufficient privileges would return a 403 Forbidden error.
Quick reference
Access Control Model Comparison
| Model | Acronym | Who Controls Access? | Best For |
|---|---|---|---|
| Discretionary Access Control | DAC | Resource owner | Small teams, file shares |
| Mandatory Access Control | MAC | System / security labels | Classified govt / military |
| Role-Based Access Control | RBAC | Administrator (via roles) | Enterprise environments |
| Attribute-Based Access Control | ABAC | Policy engine (user + resource attributes) | Fine-grained, dynamic policies |
| Rule-Based Access Control | RuBAC | System rules / ACLs | Firewall rules, network ACLs |
Go deeper
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-901 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 200-901 exam.