CCNA Foundations: NTP — Authenticated Time Sync (Client/Server)

Archive lab

Deploy an authenticated NTP hierarchy with a router acting as the trusted NTP server and two network devices as clients. Validate reachability from user hosts and confirm that clients securely synchronize to the server.

Learning objectives

• Configure an IOS router as an authenticated NTP master
• Enable and verify NTP authentication on IOS routers and L2 switches
• Point clients at the correct NTP server with a trusted key ID
• Validate time sync using show outputs and observe association state changes
• Use end-host tests to confirm network reachability supporting time sync

Troubleshooting focus

• If NTP clients never select a peer, confirm the NTP server is reachable and responding (ping, routing in place).
• If associations remain pending, check that 'ntp authenticate' is enabled and the key-id is both defined and trusted on all participants.
• If clients show a candidate/remote but never become sys.peer, ensure the same key-id is used on both ends and the MD5 strings match.
• If the switch cannot reach the server, verify the SVI IP, VLAN membership of the ports, and the ip default-gateway toward the router.