200-901 Infrastructure and Automation Practice Question
A DevOps team uses Ansible to configure Cisco Nexus switches for a new data center. They have a playbook that uses the nxos_vlan module to create VLANs and nxos_interface module to assign access VLANs. The playbook runs successfully on the first Nexus switch but fails on the second with error: 'module_stderr: ntclib: error: unable to connect to switch'. Both switches are reachable via ping and SSH from the Ansible control node. The inventory file has the same SSH credentials for both switches. What is the most likely cause of the connection failure on the second switch?
⚠ Common exam trap
Cisco often tests the misconception that Ansible nxos modules use SSH for all operations, when in fact they default to NX-API for task execution, so candidates may overlook the need for NX-API to be enabled on the target switch.
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 second switch does not have NX-API enabled.
The error 'module_stderr: ntclib: error: unable to connect to switch' indicates that the Ansible nxos modules are attempting to use NX-API (REST-like HTTP/HTTPS API) to communicate with the switch, not SSH. Even though SSH is reachable, the second switch likely has NX-API disabled or not configured, causing the connection failure. The nxos_vlan and nxos_interface modules in Ansible rely on NX-API by default when the connection type is set to 'network_cli' or 'httpapi', and without NX-API enabled, the modules cannot execute.
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 second switch does not have NX-API enabled.
Why this is correct
The error indicates NX-API connection failure; enabling NX-API resolves.
- ✗
The Ansible control node has an incompatible version of the nxos collection.
Why it's wrong here
Collection version would affect both switches equally if same playbook.
- ✗
The second switch has a different VLAN database that conflicts with the playbook.
Why it's wrong here
VLAN database conflict would produce configuration error, not connection failure.
- ✗
The second switch's SSH key fingerprint has changed and is not accepted.
Why it's wrong here
SSH key issue would cause different error, not ntclib connection error.
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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.