[Already SOLVED] Precious leases?

[Eugene Grosbein]

10.12.2017 19:08, Nicolas Ecarnot wrote:
> Hello,
> 
> This message deals with NO PROBLEM, nothing wrong, nor issue to solve.
> 
> It is just a discussion about something I don't get.
> I'm using DHCP since more than a decade in very complex failover setups, I'm using numerous script-generated hundreds of page dhcpd.conf servers amongst hundreds of synced sites.
> All this is working flawlessly.
> 
> Though, I've never understood in what cases it should be important to keep safely the dhcp lease files. I mean, for dynamic leases hosts, they just will have to issue new queries - this won't load the servers as all those hosts lease time has been randomly spread in date and time, so their queries won't burst all in the same time.
> And for the fixed lease, there is neither a hurry to get a reply because if the dhcp infrastructure replies lately, the dhcp implementation allows late query retries in time.
> 
> So, I don't see anything horrible happening if I loose all my leases files and restart my servers...?

When DHCP client tries to extend its lease time period, a server can agree and just extend the time
or it can insist on new address. In the latter case, all client's currently established long-lived
connections will break. Also, HTTP auth cookies may be bounded to the (public) IP address and they break too.

With DHCP server lease files in place, your DHCP clients get much more stable and seamless workflow
because without them, the server have no information of previous MAC/IP connections to offer same IP.