[Samba] DDNS, DHCP and AD

Rowland Penny rpenny at samba.org
Fri Dec 16 18:27:37 UTC 2022

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'.


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