[Samba] DDNS, DHCP and AD

Gregory Sloop gregs at sloop.net
Fri Dec 16 18:45:54 UTC 2022

Top posting.
I'm puzzled.
I note, specifically, that ALL dns queries for the 3rd level domain that AD is in, get forwarded to the AD internal DNS servers.
It's not that DNS lookups are failing, but that the *DDNS* records for stations aren't updated in AD.
(So a AD joined station moves from one subnet to another, or gets a new IP lease on a different IP, but the *DDNS* A record (in AD only) doesn't get updated to point at the new lease it got from the non-AD-aware DHCP server.)
So, lets just assume I want to "fix" this - and ignore if I *should* or not.

You suggest that clients could update their AD records on their own. (Not having DHCPD do so.)
Can you point me at a wiki article that describes how to do this?
[I'm worried that we don't understand each other well, and that you misunderstand what's going on, due to your saying I should point all AD dns queries to AD DNS servers, which I'm already doing.]


> On 16/12/2022 18:02, Greg Sloop <gregs--- via samba wrote:

>> Bump.
>> Anyone?

>>> On Thu, Dec 8, 2022 at 12:02 PM Greg Sloop <gregs at sloop.net> <
gregs at sloop.net>>> wrote:

>>>> Looking for general theory here - perhaps this will devolve into more "how
>>> to" later, but right now I need overall understanding.

>>> We handle DHCP outside AD. We also do DDNS there, and handle DNS lookups.

>>> Here's what the current setup looks like

>>> We have a pair of DHCP servers (ISC DHCPD) and those same boxes handle DNS
>>> for the network. They're in the DNS domain of, lets say; xyz.local. (Yes,
>>> we're using local. Can't easily dig it out. We'll live with any AVAHI
>>> side-effects, I think - at least for now.)

>>> The AD domain is ad.xyz.local. (so a server is something like
>>> s1.ad.xyz.local)

>>> The DHCP/DNS servers handle multiple ip subnets and setup the forwards and
>>> reverses for dhcp leases - into the xyz.local domain.

>>> These xyz.local BIND servers forward all queries about *.ad.xyz.local to
>>> the AD servers, so queries about the AD domain get handled properly. All
>>> non AD queries they handle internally - recursively or not.

>>> However, we also get DDNS entries into AD. (I've never set this up,
>>> explicitly, up this, so it's happening "automagically.")

>>> Something like station-1.ad.xyz.local.
>>> But we'll sometimes end up with mismatches between the ad and non-ad
>>> forwards/reverses. (station1.ad.xyz.local points to a "wrong" ip, where
>>> station1.xyz.local doesn't)

>>> So, the base question is;
>>> Is there any reason for us to worry about ad.xyz.local DDNS entries being
>>> "correct" in AD's DNS entries?

>>> I suppose if we share resources via AD for a host that gets a DHCP
>>> addresses, and we references those resources via name, we'll have issues.
>>> But outside of that case, is there any reason to try to keep the
>>> ad.xyz.local forwards "correct?"

>>> If I can live with DNS lookups like station1.xyz.local - can I just ignore
>>> the DDNS entries in AD for stations? (Without dire outcomes somewhere that
>>> I haven't considered.)

>>> Thoughts?
>>> Is there a wiki article that covers this? (I didn't find one and I can't
>>> easily find a discussion thread that seems closely relevant.

> Your problem is that, whilst you may ignore the dns records in AD, your domain clients might not. You have seen that your clients are trying to update their records in AD (you can turn this off), they will also be doing other things under the hood.

> I have always suggested that if you are going to use an external dns server, this server should always forward anything for the AD domain to an AD DC. This way, you do not get any problems. If you check on the internet for AD problems, there are long running responses, 'it is DNS' or 'it was DNS'.

> Rowland


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