[Kea-users] DHCP4 reservation by DNS hostname lookup - how?

[Darren Ankney]

Hi Jeff,

Please be aware that ISC DHCP only looked up these DNS entries when
the process started.  So if you ran the ISC DHCP process for many
months, the notion that ISC DHCP had of these endpoint IP addresses
would diverge from what was currently in DNS if there were changes.
It was misleading to users such as yourself who thought that lookups
were ongoing when they were not.

Thank you,
Darren Ankney

On Thu, Oct 10, 2024 at 3:26 AM Jeff Armstrong <jeff at whitefern.com> wrote:
>
> Isn't this a major loss of functionality? Is there a plan / ticket to add this core feature?
>
> Manually maintaining IP reservations in multiple places (DNS, Reverse DNS and DHCP) is a pita that is prone to error.
>
> Decisions on IP range allocation fit more naturally in DNS as pre-release testing there can confirm that both forward and reverse IP allocation is consistent.
>
> Surely you don't expect DevOps to maintain forward IP allocation in DHCP and reverse allocation in DNS?
>
> Regards,
>
> Jeff
>
> On 09/10/2024 17:01, Peter Davies wrote:
>
> Hi Jeff,
>    You cannot use a fqdn in place of an address within a host reservation in Kea.
>
> Kind Regards Peter
>
> ________________________________
> From: "Jeff Armstrong" <jeff at whitefern.com>
> To: "Kea-users at lists.isc.org" <kea-users at lists.isc.org>
> Sent: Wednesday, 9 October, 2024 17:10:39
> Subject: [Kea-users] DHCP4 reservation by DNS hostname lookup - how?
>
> In the isc-dhcp-server I could use DNS to make reservations:
>
> host gh-ja-iphone-uk { hardware ethernet 5b:c7:43:37:a2:b0; fixed-address ja-iphone-uk.gh.mydomain.com; }
> and the IP assigned would be retrieved from DNS.
>
> In Kea I have tried:
>
>     "reservations": [
>       { "hw-address": "5b:c7:43:37:a2:b0", "fixed-address": "ja-iphone-uk.gh.mydomain.com" }
>     ]
>     "reservations": [
>       { "hw-address": "5b:c7:43:37:a2:b0", "ip-address": "ja-iphone-uk.gh.mydomain.com" }
>     ]
>     "reservations": [
>       { "hw-address": "5b:c7:43:37:a2:b0", "host-name": "ja-iphone-uk.gh.mydomain.com" }
>     ]</ div>
> but these don't work - the first two stop the server from starting with a configuration error, and the third just assigns from the pool.
> I have read https://kea.readthedocs.io/en/kea-2.6.1/arm/dhcp4-srv.html#host-reservations-in-dhcpv4 - but cannot find a clear list of all the recognised options for reservations.
> Help?!?
> Many thanks,
> Jeff
>
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