Static IP and IP management

Simon Hobson dhcp1 at
Wed Feb 24 19:15:02 UTC 2016

Chuck Anderson <cra at WPI.EDU> wrote:

> You can do that, but you have to use "reserved" leases rather than
> fixed-address statements.  ISC dhcpd doesn't track the expiry of
> fixed-address leases.

To expand on that ...

When you use a fixed-address statement to assign an address, no actual lease is created. Since it's a fixed address, there's no real need for it - so the server takes a shortcut, replies to the client, but doesn't actually store anything. So the only DNS update possible is when the "lease" is given out.

A relatively new feature is a "reserved" lease. It acts the same as an ordinary lease - including normal expiry and DNS updates/removals - with the one difference of being tied to a single client.
To use this feature, you need to either modify an existing lease (add the "reserved" statement), or you should be able to create a skeleton lease (including reserved statement) in advance of the client connecting.

In either case, you probably need to be learning OMAPI to interact with the server !

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