move lease file?

[Simon Hobson]

Bernd Nachtigall <bnacht at web.de> wrote:

> I plan to setup a new DHCP hardware. (Configuration is not changed)
> It is necessary to copy the old dhcpd.leases to the new server  to get an 
> noiseless move?

Yes, if you are replacing the DHCP server, then you should copy the leases file from the old server to it.

If you don't then you are starting up a new server which has no knowledge of "promises" made by it's predecessor.
While many clients will simply come to renew, ask for their previous address, and the server will then know about that client and IP - that won't happen for everything. So you are also likely to find clients (re)joining the network, the server will pick an address which it's own records say is free - then find that the address is in use. Depending on various factors (especially if the devices already using teh address has firewalled off pings*), you will either get leases flagged as abandoned (which then are effectively taken out of your free pool), or the client will be offered a duplicate address which it should then find for itself is already in use. You are also likely to see a certain amount of address churn.