Hi Christoph, On Tue, Dec 2, 2025 at 9:07 PM Christoph Markert <[email protected]> wrote: > > Hi Darren, > > please find the log attached. You can see that after around 6min KEA uses the > defined hostname. > Could you please elaborate a bit more on the prefix delegation part. Why > would I need it?
You probably don't need it unless this is some kind of router with a network behind it that needs subnet assignment. Prefix delegation (IA_PD) is meant to distribute one or more subnets for use as an "inside" network since NAT, generally speaking, is not used in IPv6 (at least not in the same way it was in IPv4). You can read all of the details about it here: https://datatracker.ietf.org/doc/html/rfc8415#section-6.3 It is safe to not configure a prefix delegation subnet. You would know if you needed to. I see what happened here though I don't know why. Initially when your client obtained the ip address (IA_NA) via a full SARR (solicit->advertise->request->reply). It did ask for an IA_PD during this time as well. During the advertise, Kea sent back a blank FQDN. During the Reply, Kea generated a dynamic hostname and returned this in option 39 after first logging about a partial FQDN in incoming option 39. Sometime later, the client asks for only an IA_PD and does not include option 39 (FQDN). Therefore, Kea does not complain about the FQDN being partial. Kea sends back the correct hostname as created with the reservation + the qualifying suffix. A subsequent full SARR sometime later results in Kea again sending the correct FQDN again. I do not know the reason for this behavior; why it failed on the initial SARR. I had a look at https://www.rfc-editor.org/rfc/rfc4704.html which describes option 39, and expected server and client behavior but nothing jumped out at me. It may be correct behavior based on a subtle reading of the RFC, or it may be a bug. In any case, I guess it works after a short time... If you think it is a bug perhaps you could open an issue in Gitlab: https://gitlab.isc.org/isc-projects/kea/-/issues Thank you, Darren Ankney -- ISC funds the development of this software with paid support subscriptions. Contact us at https://www.isc.org/contact/ for more information. To unsubscribe visit https://lists.isc.org/mailman/listinfo/kea-users. [email protected]
