Anyone have experience with setting up their Nexus 7k core as an NTP server?

I was thinking the code would look like below:

ntp master stratum 2
ntp server ns.arc.nasa.gov prefer
ntp server bitsy.mit.edu
ntp source-interface vlan 1 
  • Aside from 'that will work', what are your concerns with this setup?
    – Ryan Foley
    Aug 25, 2014 at 14:41
  • I just wanted to know if this would allow us to use the 7k as the authoritative time server for our network. I understand that it could be a bit more secure, but I just wanted to get the ground work in place.
    – BaconManic
    Aug 25, 2014 at 14:47

1 Answer 1


That is all you need to get going, however it isn't an ideal configuration. I'll ignore security and local NTP architecture and focus on your current config.

The minimum recommended NTP servers is generally 3, but preferably 4. The reason for this is not only resiliency but it gives the client (your N7k) a better reference if any of the upstream servers start experiencing issues or clock drift.

With NTP, when a server is well out of sync, the client will disregard it as a valid source (even if it is a higher stratum than the others!). If you have two servers configured then how do you tell who is out of sync? The third server gives the client another point of reference that can be used to tell who is out of sync (the more the merrier, up until a certain point).

Also, I think bitsy.mit.edu is a Stratum 3 - you might be able to find a few Stratum 2 servers that are close by instead. If you have a reason for those particular servers then feel free to ignore this.

Tl;dr yes it will work.

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