I'm currently designing a system (a physical system that can be used where ever) and have run into the issue that on some networks internet NTP servers can be blocked (by a firewall). In those cases there always are local NTP servers available. Maybe even the DHCP offers some.

Now how do I get the NTP daemon to look for those local ones (either sending a broadcast itself or looking for advertisement broadcasts) and to accept any offered over DHCP while still using (or trying to use) the pools configured in the config.


Getting specific NTP servers from DHCP to use in Client/Server mode is the better choice. If that doesn't work in your environment, have a look at NTP Broadcast Mode, and see if your local NTP servers are set up to respond to broadcast requests.


  • The idea is that I have a systems of fallbacks because this ends up machines that may be deployed anywhere where I don't have any control over. – BrainStone Feb 21 '20 at 22:34
  • Given that networks can be static address only, and out of your control, and NTP servers can be set to forbid broadcast mode, also out of your control. you might be stuck with having to include a list of minimum requirements for installation. – dafydd Feb 23 '20 at 4:14

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