AWS Certified Advanced Networking – Specialty (ANS-C00) — Question 367

Your company uses an NTP server to synchronize time across systems. The company runs multiple versions of Linux and Windows systems. You discover that the NTP server has failed, and you need to add an alternate NTP server to your instances.
Where should you apply the NTP server update to propagate information without rebooting your running instances?

Answer options

• A. DHCP Options Set
• B. instance user-data
• C. cfn-init scripts
• D. instance meta-data

Correct answer: A

Explanation

Updating the DHCP Options Set allows you to specify a new NTP server for a VPC, and the running instances will automatically pick up the change when their DHCP leases renew without needing a reboot. In contrast, modifications to instance user-data or cfn-init scripts only execute during the initial launch phase of an instance and would require recreation or a reboot to apply. Instance meta-data is read-only and cannot be used to configure network services like NTP.