Question

A security engineer is hardening the infrastructure devices in a data center. Accurate, trusted time is required so that syslog and certificate validation are reliable, and the engineer must ensure that routers only synchronize with an authorized internal NTP server and reject rogue time sources. Which configuration approach on the client routers meets this requirement?

Accepted Answer

Configure the NTP server address using the 'ntp server' command and enable 'ntp authenticate' with a defined authentication-key and a matching 'ntp trusted-key'

Answer

Configure the NTP server address and apply an access-list with 'ntp access-group serve-only' referencing the server subnet

Answer

Configure 'ntp master 3' on each client router so they maintain their own stratum and ignore external sources

Answer

Configure the NTP server address and set 'ntp source Loopback0' so time is only accepted from the loopback interface