question: configuration changes

Simon Hobson dhcp1 at
Thu Nov 5 17:29:55 UTC 2020

ahiya <ahiya at> wrote:

> hi Allis it possible to change the config on ISC DHCP without restarting the
> service?

They made the decision many years (decades !) ago that it was not worth the cost to do so. Except in fairly unusual circumstances, service startup is very quick and so there should be no impact on service by doing a stop-start.
To do a live reconfig would mean either writing, testing, **and maintaining** code to dynamically update in-memory tables; or would simply replicate what is done now when stopping and starting the service. As already mentioned, you can test a new config using the -t flag before restarting the service.

At the time when this decision was made, networks were generally a lot simpler, and there wasn't much demand for dynamic reconfig - certainly no-one wanting to sponsor it's development. "Networks were simpler back then" also explains some of the design decisions that might not seem to make sense these days !

I have no experience with it myself, but AIUI KEA is intended to be a more modern replacement for dhcpd. It may be worth investigating if that might fit your needs better.


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