200-901 Question #397: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. An administrator attempts to perform a GET operation by using the Cisco IOS XE RESTCONF API to return the hostname of a device. The sequence diagram in the exhibit illustrates the HTTP messages observed. Which change to the API request resolves the issue?

Options

• ARemove the -H 'Accept: application/yang-data+json' header.
• BReplace -u cisco:cisco parameter with -u 'cisco:cisco'.
• CChange the request method from -X 'GET' to -X 'POST'.
• DAdd the -H 'Content-Type: application/yang-data+json' header.

Explanation

Credentials passed to curl's -u flag must be quoted so the shell does not misinterpret the colon or other characters, preventing authentication failures against the RESTCONF API.

Common mistakes.

• A. The 'Accept: application/yang-data+json' header controls the response format negotiated with the server - removing it affects content negotiation, not the authentication failure shown in the sequence diagram.
• C. GET is the correct HTTP method for retrieving data such as a hostname from a RESTCONF endpoint; changing to POST would attempt resource creation and is semantically incorrect for a read operation.
• D. The 'Content-Type' header describes the format of a request body sent to the server, which is absent in a GET request; adding it does not affect authentication and would not resolve a 401 error.

Concept tested. RESTCONF API curl authentication credential quoting

Reference. https://developer.cisco.com/docs/ios-xe/restconf/

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