Script to run on DHCPNAK

Thu Jul 20 12:45:08 UTC 2017

Mark, 

That is completely normal. The device 00:03:e6:6f:42:14 previously had an address of 192.168.100.20 and attempted to renew such address. Apparently that address is not valid on the network your DHCP server is on. So, a NAK was sent followed by a discover from the client. The client and server then negotiated a 10.4.2.191 address. 

What is the actual problem that you are having as I am not sure this has anything to do with it... 

> From: "Mark Spring" <mspring at nktelco.com>
> To: "Users of ISC DHCP" <dhcp-users at lists.isc.org>
> Sent: Thursday, July 20, 2017 8:31:30 AM
> Subject: Re: Script to run on DHCPNAK

> isc, just one server here is an example
> Jul 19 10:04:36 dhcp dhcpd: DHCPREQUEST for 192.168.100.20 from
> 00:03:e6:6f:42:14 via [ http://10.4.0.1/ | 10.4.0.1 ] : wrong net
> Jul 19 10:04:36 dhcp dhcpd: DHCPNAK on 192.168.100.20 to 00:03:e6:6f:42:14 via
> 10.4.0.1
> Jul 19 10:04:39 dhcp dhcpd: DHCPDISCOVER from 00:03:e6:6f:42:14 via 10.4.0.1
> Jul 19 10:04:40 dhcp dhcpd: DHCPOFFER on 10.4.2.191 to 00:03:e6:6f:42:14 via
> 10.4.0.1
> Jul 19 10:04:40 dhcp dhcpd: DHCPREQUEST for 10.4.2.191 (192.168.100.3) from
> 00:03:e6:6f:42:14 via 10.4.0.
> Jul 19 10:04:40 dhcp dhcpd: DHCPACK on 10.4.2.191 to 00:03:e6:6f:42:14 via
> 10.4.0.1

> Mark Spring
> Information Systems Manager

> On Thu, Jul 20, 2017 at 8:22 AM, perl-list < [ mailto:perl-list at network1.net |
> perl-list at network1.net ] > wrote:

>> Are the NAK and ACK coming from the same server? Can you post example log
>> messages of the NAK and ACK and related communication? I assume this is ISC
>> DHCP that we are speaking of and not some proprietary DHCP server?

>>> I am having some issues with network gear, and while arguing with vendors about
>>> who's problem it really is..I noticed that my device receives a NAK before it
>>> receives the proper IP address from our server(when the gear comes back
>>> online). If I can track this down in the logs then I can look for the ACK that
>>> follows, login to the device and reboot it properly.

>>> ___
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