350-401 Automation Practice Question
A network engineer is writing a Python script to retrieve the operational state of a GigabitEthernet interface from a Cisco IOS XE device using RESTCONF. The script sends a GET request to https://10.1.1.1/restconf/data/ietf-interfaces:interfaces/interface=GigabitEthernet1 but receives a 406 Not Acceptable response. The device supports RESTCONF and the interface exists. Which HTTP header should the engineer add to the request to resolve this error?
⚠ Common exam trap
Watch out — candidates often confuse the Accept header, which specifies the desired response format, with the Content-Type header, which specifies the format of the request body, leading to an incorrect fix.
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
✓
Accept: application/yang-data+json
The 406 Not Acceptable status code indicates that the server cannot produce a response matching the Accept header. In RESTCONF, the client must specify the desired media type, such as application/yang-data+json, to retrieve data in JSON. Without it, the server may reject the request. Adding the correct Accept header resolves the negotiation issue.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Accept: application/xml
Why it's wrong here
While application/xml is a valid media type for RESTCONF, the error indicates the server cannot satisfy the requested Accept type. If the original request had no Accept header, the server might default to XML, but the 406 suggests a mismatch. Specifying XML could work only if the device supports XML, but JSON is the typical choice for Python scripts, and the question implies JSON is needed.
- ✓
Accept: application/yang-data+json
Why this is correct
RESTCONF requires the client to specify the desired media type for the response. The 406 Not Acceptable error occurs when the Accept header is missing or does not match a media type the server can produce. Adding Accept: application/yang-data+json tells the server to return the data in JSON format, which IOS XE supports, resolving the error.
- ✗
Authorization: Basic YWRtaW46YWRtaW4=
Why it's wrong here
The Authorization header is used for authentication. If authentication failed, the server would return 401 Unauthorized, not 406 Not Acceptable. Since the error is 406, the credentials are likely already accepted or the issue is not authentication. Adding Authorization would not fix the media type negotiation problem.
- ✗
Content-Type: application/yang-data+json
Why it's wrong here
The Content-Type header describes the media type of the request body. For a GET request, there is typically no body, so Content-Type is not required and does not affect the 406 error. The 406 is about the response format the client can accept, which is controlled by the Accept header, not Content-Type.
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SDN Controllers and Cisco ACI
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.
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.
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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
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