Final answer:
The 'ntp server' command puts the current router into static Client mode, where it synchronizes its time with the specified NTP server.
Step-by-step explanation:
The command 'ntp server <server-IP>' puts the current router into static Client mode. In this mode, the router is configured to synchronize its time with the specified NTP server. The router acts as a client and retrieves time information from the NTP server to keep its clock synchronized.