[Cialug] DHCP Server: how can a client get the same IP after restart?

[Tad Anhalt]

Nathan C. Smith wrote:
> 
> Recently I switched to using the Linux DHCP server on redhat 9 distribution
> instead of my firewall.  I really like being able to specify IP addresses by
> MAC address.  However, It seems with other DHCP implementations the server
> would reserve the address even when the machine was off any the machine
> could get the address again when it started up.

   Which dhcp server are you using?  I'm pretty sure that ISC does this 
by default, but I'll admit that it's been a long time since I've used 
anything but fixed-address so my recollection may be faulty.

   The man page (under the heading "DYNAMIC ADDRESS ALLOCATION") seems 
to back that up.

http://www.daemon-systems.org/man/dhcpd.conf.5.html

   You could also set the "min-lease-time" if you think it's an issue of 
the client(s) requesting too short of a lease time.

   Check the leases file for the last entry containing the MAC of the 
host you are trying to debug.  The "ends" tag will show the expiration 
time (in UTC!).  Subtract "starts" from "ends" and make sure it looks 
like what you expect.

   It sounds like some of the machines on your network behave as 
expected and others don't?  What difference do you see in the logs 
between one that keeps it's IP and one that doesn't?

Tad