hardMultiple ChoiceObjective-mapped

200-901 Practice Question: Attempts to modify the IP address of…

Exhibit

Refer to the exhibit.
RESTCONF request:
GET /restconf/data/Cisco-IOS-XE-native:native/interface/GigabitEthernet=1/0/1
Headers:
Accept: application/yang-data+json
Response:
{
  "Cisco-IOS-XE-native:GigabitEthernet": [{
    "name": "1/0/1",
    "description": "Connected to core",
    "ip": {
      "address": {
        "primary": {
          "address": "192.168.1.1",
          "mask": "255.255.255.0"
        }
      }
    }
  }]
}

A network engineer attempts to modify the IP address of GigabitEthernet1/0/1 using the Cisco IOS-XE RESTCONF API. They send a PUT request with a modified JSON body but receive a 400 Bad Request error. What is the most likely cause?

⚠ Common exam trap

Cisco often tests the distinction between PUT (full replacement) and PATCH (partial update) in RESTCONF, and the trap here is that candidates mistakenly think a 400 error is due to missing headers or API availability, rather than recognizing that PUT requires the complete resource hierarchy in 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

✓

The request body does not include the full resource hierarchy.

D is correct because RESTCONF requires the request body to contain the full resource hierarchy (e.g., the entire YANG data tree for the interface) when using PUT, as PUT is a full replacement operation. A 400 Bad Request error typically indicates a malformed request, and omitting mandatory parent or sibling nodes in the JSON body violates the YANG schema, causing the server to reject the request.

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 Accept header should be application/json.
Why it's wrong here
The Accept header shown is correct for RESTCONF (application/yang-data+json). Changing to application/json may not be supported.
✗
The Content-Type header is missing or set incorrectly.
Why it's wrong here
While Content-Type is required, the error here is more likely due to incorrect request body structure; a missing header would cause a different error.
✗
The API is not enabled on the device.
Why it's wrong here
If the API were disabled, the response would be 404 Not Found or connection refused, not 400.
✓
The request body does not include the full resource hierarchy.
Why this is correct
RESTCONF PUT requires the entire data tree for the resource. Omitting parent containers leads to 400.

Go deeper

200-901 Practice Question: Attempts to modify the IP address of…

Exhibit

Why each option matters

Option-by-option breakdown

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