[Kea-users] DDNS limitations - ddns-qualifying-suffix vs domain-name

[Darren Ankney]

Hi Vladimir,

I thought about that, but that wouldn't necessarily work.  Without
looking up the provided hostname, Kea wouldn't understand if it should
add the suffix or not (i.e., is it a complete name?)  For example:

- suffix could be 'example.org'
- 'example.org' might have sub domains such as 'office.example.org'
and 'warehouse.example.org'
- so there may be hostnames like 'laptop1.office' and
'laptop2.warehouse' that would need example.org appended to them.

Kea couldn't know this isn't the case without some other flag or some
very complex (very slow) lookup logic to try to figure out what the
administrator intends to happen.

Thank you,

Darren Ankney

On Sun, Oct 22, 2023 at 10:33 AM Vladimir Nikolic <vladimir at nikolic.si> wrote:
>
> Hi Darren,
>
> > There would have to be some way to flag hostnames that you wanted to
> > ignore a ddns-qualifying-suffix setting somehow to have it
> > simultaneously set to some value and not apply to all hostnames in
> > that block.
>
> Yeah, like if you end "hostname" parameter (within a host reservation)
> with a ".", then KEA should treat it as a FQDN, and not append
> "ddns-qualifying-suffix" from the subnet definition.
>
> Regards,
> Vladimir
>
> On 2023-10-21 18:54, Darren Ankney wrote:
> > Hi Vladimir,
> >
> > You can set it "ddns-qualifying-suffix": "", which resets it to empty
> > in the block in which you do that.  You could also only specify inside
> > subnets where you need it specified and not specify at global level.
> > There would have to be some way to flag hostnames that you wanted to
> > ignore a ddns-qualifying-suffix setting somehow to have it
> > simultaneously set to some value and not apply to all hostnames in
> > that block.
> >
> > Thank you,
> >
> > Darren Ankney
> >
> > On Tue, Oct 17, 2023 at 2:50 AM Vladimir Nikolić <vladimir at nikolic.si>
> > wrote:
> >>
> >> Thanks Darren.
> >>
> >> If ‘ddns-qualifying-subnet’ is being set on any level, it’s then
> >> appended to the ‘hostname’ value from the host reservation. ‘hostname’
> >> is the FQDN, only if ‘ddns-qualifying-subnet’ is empty.
> >> So it’s either one or another.
> >> Which is really inflexible.
> >>
> >> Regards
> >>
> >>
> >> > On 17 Oct 2023, at 12:26 am, Darren Ankney <darren.ankney at gmail.com> wrote:
> >> >
> >> > Hi Vladimir,
> >> >
> >> > The DHCPv4 domain-name option (15) isn't meant for use with ddns.  It
> >> > is a search domain that the client should use when performing name
> >> > resolution.  See: https://www.rfc-editor.org/rfc/rfc2132#section-3.17
> >> >
> >> > You can set ddns-qualifying-suffix at the global, shared-network and
> >> > subnet level.  In a host reservation, you can use the "hostname"
> >> > parameter to specify a FQDN to send to the client and for use in DDNS.
> >> > See here: https://kea.readthedocs.io/en/kea-2.4.0/arm/dhcp4-srv.html#reserving-a-hostname
> >> >
> >> >> On Mon, Oct 16, 2023 at 3:23 PM Vladimir Nikolic via Kea-users
> >> >> <kea-users at lists.isc.org> wrote:
> >> >>
> >> >> Hi,
> >> >>
> >> >> While trying to migrate DHCP service from ISC DHCP to ISC KEA, we are
> >> >> hitting following KEA limitations:
> >> >>
> >> >> - option domain-name has no part in DDNS names construction, it's only
> >> >> ddns-qualifying-suffix that's being honoured
> >> >> - ddns-qualifying-suffix can't be specified in the class definition (we
> >> >> have dedicated zone for our OOB devices)
> >> >> - there can be only one DDNS zone for all the clients in a subnet
> >> >> (ddns-qualifying-suffix), with ISC DHCP you can have one default
> >> >> domain-name for a subnet and every single host reservation with a
> >> >> different domain-name (DDNS zone)
> >> >>
> >> >> Regards,
> >> >> Vladimir
> >> >> --
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