350-401 Automation Practice Question
A network engineer is building a Python script to configure a Cisco IOS XE device via RESTCONF. The script sends a POST request to the URI https://10.1.1.1/restconf/data/ietf-interfaces:interfaces with the JSON payload shown. The device returns HTTP 415 Unsupported Media Type. Which change to the script will resolve the error?
⚠ Common exam trap
Many exam-takers confuse the Accept header (which specifies the desired response format) with the Content-Type header (which specifies the format of the request body).
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
✓
Add the header 'Content-Type: application/yang-data+json' to the request.
RESTCONF uses HTTP and requires standard headers to indicate payload format. When sending JSON, the Content-Type header must be set to application/yang-data+json. The server uses this to select the correct parser. Without it, the device returns 415 Unsupported Media Type, indicating it cannot process the body.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Add the header 'Accept: application/yang-data+json' to the request.
Why it's wrong here
The Accept header tells the server what response format the client prefers (e.g., JSON). It does not specify the format of the request body. The 415 error is caused by the server rejecting the request payload's media type, so Accept alone will not resolve it. The Content-Type header is needed instead.
- ✗
Include authentication credentials in the request body.
Why it's wrong here
Authentication is typically handled via HTTP Basic Auth headers or tokens, not in the body. Even if authentication were missing, the server would return 401 Unauthorized, not 415. The 415 status specifically indicates an unsupported media type, so adding credentials to the body would not address the root cause.
- ✗
Change the HTTP method from POST to PUT.
Why it's wrong here
Changing to PUT would not fix the 415 error because the server still cannot interpret the payload without the correct Content-Type header. PUT is used to replace a resource, while POST creates one; the method choice does not address the media type issue. The error is about payload format, not method.
- ✓
Add the header 'Content-Type: application/yang-data+json' to the request.
Why this is correct
RESTCONF requires the Content-Type header to be application/yang-data+json when sending a JSON payload. Without it, the device cannot determine the payload format and returns 415. Adding this header tells the server the body is YANG data encoded in JSON, allowing it to parse and apply the configuration.
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Key term
NETCONF Protocol
NETCONF is a network management protocol that uses a structured data format to configure, retrieve, and modify network devices in a standard, programmatic way.
Key term
REST API for Network Devices
A REST API for network devices is a set of rules that allows software applications to communicate with routers, switches, and firewalls using standard web methods like GET, POST, PUT, and DELETE over HTTP or HTTPS.
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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.