CCNP Automation Practice Question
A network engineer is writing a Python script to retrieve the operational status of all GigabitEthernet interfaces from a Cisco IOS XE device using NETCONF. The script establishes an SSH session to the device on port 830 and sends a <get> RPC with a subtree filter. The device responds with an <rpc-error> indicating 'unknown-element' for the filter. Which action should the engineer take to resolve this issue?
⚠ Common exam trap
The trap here is assuming that changing the NETCONF transport or session parameters will fix a filter validation error, when the issue is actually a mismatch between the filter and the supported YANG models.
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
✓
Verify that the YANG model for the interface operational data is supported and use the correct namespace in the filter.
The 'unknown-element' error in NETCONF indicates that the filter references a data node that the device does not recognize. This typically happens when the YANG model is not supported or the namespace is incorrect. The engineer must verify that the device supports the relevant YANG model and that the filter uses the correct namespace and node names.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Verify that the YANG model for the interface operational data is supported and use the correct namespace in the filter.
Why this is correct
The 'unknown-element' error occurs when the filter references a data node that is not defined in any YANG model supported by the device or when the namespace is incorrect. The engineer must confirm that the device supports the ietf-interfaces or Cisco-specific interface YANG model and that the filter uses the exact namespace and node names from that model.
- ✗
Convert the subtree filter to an XPath filter and resend the <get> RPC.
Why it's wrong here
While XPath filters are valid in NETCONF, simply changing the filter type does not guarantee that the referenced nodes exist in the device's YANG models. If the element is unknown, the XPath filter would also fail unless the correct namespace and node names are used. The root cause is the filter content, not the filter syntax.
- ✗
Change the NETCONF transport from SSH to TLS by enabling the netconf-tls feature on the device.
Why it's wrong here
NETCONF over TLS is a valid transport, but the error is not related to the transport layer. The <rpc-error> indicates a problem with the content of the filter, not the connection security. Changing to TLS would not resolve an unknown-element error because the device would still reject the filter if the YANG model or namespace is incorrect.
- ✗
Increase the NETCONF session timeout on the device using the netconf max-sessions command.
Why it's wrong here
The netconf max-sessions command limits the number of concurrent NETCONF sessions and does not affect filter validation. The error 'unknown-element' is a protocol-level validation error, not a session timeout issue. Adjusting session limits would not change how the device parses the subtree filter.
Visual reference
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.