R1 as an NTP server must have:• NTP authentication enabled• NTP packets sourced from Interface...

Option B. Infrastructure services must be identified by their exact function: monitoring, time, address assignment, file transfer, logging, or traffic treatment. Cisco CCNA 200-301 v1.1 includes this under IP Services, where the exam expects engineers to recognize the device behavior that actually produces the required outcome. The question is best solved by reading the operational clue rather than choosing a familiar acronym. The distractors name real services, but those services do not perform the action requested in the prompt. In a production network, the wrong choice would normally create an outage, leave a management or security gap, or send troubleshooting toward the wrong subsystem. The selected answer is the one that matches the control-plane, data-plane, wireless, security, services, or automation mechanism described in the question. That is why it remains the verified answer for this item.