NTP question

Lunchbocks · January 2020

I have some questions about the ntp master command. First, why would I need a router set as master? Couldn’t I just issue the ntp server command and point my other Cisco devices to it with the same command? Does the ntp master do anything else or have benefits that the ntp server doesn’t offer?

Second, from what I have found, all I need to do is type ntp master <stratum #>. If this is true, how do I point the master device to an internet time source? I can’t see a master device relying on it's own time source. I have been researching this all day and I can’t seem to find the answer.

DCD · January 2020

"NTP master" command is used to make the router act as an ntp server with it's own hardware clock as a source.

In a network without Internet connectivity, such a time source may not be available. The ntp master command is used in such cases.

A system with the ntp master command configured that cannot reach any clock with a lower stratum number will claim to be synchronized at the configured stratum number, and other systems will be willing to synchronize to it via NTP.

Lunchbocks · January 2020

OK, that makes sense. The part I was struggling with is why would you do that in a network when you can sync to an external nat server. But using it in a network that doesn't have Internet access makes perfect sense.

Thanks for helping me clear this up!

NTP question

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