Windows – What happens if the DHCP server comes online after the client devices do

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If I have a Windows PC running a DHCP server. I expect it will take on order of minutes a few to boot. My network will have a variety of other devices from various vendors that will boot within seconds.

I have not found a "standard" for DHCP client retries. Will those devices timeout before the Windows DHCP server starts? If so, what is the best way to deal with that?

Clarifications:
There are no Windows clients involved. The clients are industrial embedded devices such as cameras, heaters, and robots.

I am not worried about what happens if the DHCP server goes down. These are embedded devices that are all hooked to a single power source. I want to know what to do when the "factory" powers on in the morning.

Best Answer

OK, I have a couple thoughts:

  1. There are as many DHCP stacks as there are stars in the sky. OK, not quite, but you get the idea. Embedded networking stacks are especially known for having non-complete "standards" implementation. As such, it's highly likely that your devices will end up booting before your DHCPd is ready, will APIPA, and won't ever retry DHCP. The only way you can verify this is to check the behavior of each device involved.
  2. Power-cycling the switch (as others have recommended) may not even work. I've seen many embedded devices that fire off their DHCP requests once as part of the boot sequence and then never try again, even if the PHY link state on the NIC changes.

Here is my recommended solution:

There are available on the market power-sequencing PDUs. These are typically two or three-stage PDUs with programmable delays. With these, when they're powered on, they'll power up the first stage, wait the specified number of seconds, power up the second stage, etc. You could connect your switch and your server to the first stage, have the PDU wait 5 minutes for the server to complete booting and then power up the second stage which has all of the other devices on it.

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