Redundant Time Sources with prefer

Bundle lab · $29.99

Build a small LAN with two IOS routers acting as NTP masters at different strata and a client that lists both as time sources, preferring one using the prefer keyword. All routers share a single broadcast domain via a Layer-2 switch, with no routing configured. You will deploy deterministic NTP, verify associations, and understand redundancy selection behavior.

Learning objectives

• Configure two IOS routers as authoritative NTP masters at different strata
• Configure a client router to use multiple NTP servers and prefer one source
• Verify NTP associations and system peer selection with show commands
• Explain how prefer biases selection when multiple usable sources exist

Troubleshooting focus

• Wrong or missing ntp master on a server prevents client selection
• Incorrect server IP or interface down on the client
• Prefer keyword on the non-existent or unreachable server has no effect
• Clock sync requires time; do not misinterpret transient output