200-901 Question #221: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. Which JSON snippet configures a new interface according to YANG model? A. B. C. D.

Options

• A"ietf-interfaces": { "interface": { "name": "Loopback100", "enabled": true, "ietf-ip:ipv4": { "address": [ { "ip": "10.255.254.1", "netmask": "255.255.255.0" } ] } } }
• B"interface": { "name": "Loopback100", "enabled": true, "ietf-ip:ipv4": { "address": [ { "ip": "10.255.254.1", "netmask": "255.255.255.0" } ] } }
• C"ietf-interfaces:interface": { "name": "Loopback100", "enabled": true, "ietf-ip:ipv4:address": [ { "ip": "10.255.254.1", "netmask": "255.255.255.0" } ] }
• D"ietf-interfaces:interface": { "name": "Loopback100", "enabled": true, "ietf-ip:ipv4": { "address": [ { "ip": "10.255.254.1", "netmask": "255.255.255.0" } ] } }

Explanation

{"question_number": 10, "correct_answer": "D", "explanation": "In RESTCONF with YANG models, the correct JSON payload format requires the top-level key to use the 'module:container' namespace prefix notation. The ietf-interfaces YANG model defines the container 'interface' under the module 'ietf-interfaces', so the correct top-level key is 'ietf-interfaces:interface'. Inside, the ietf-ip augmentation for IPv4 is correctly referenced as 'ietf-ip:ipv4', with a nested 'address' array containing 'ip' and 'netmask' fields. Option A wraps everything under 'ietf-interfaces' as a module container, which is incorrect structure. Option B omits the required module namespace prefix on 'interface'. Option C incorrectly flattens the ietf-ip:ipv4 address structure into a single colon-separated key instead of proper nested objects.", "generated_by": "claude-sonnet", "llm_judge_score": 4}

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