[Samba] DHCP Updates to DNS - Multiple Entries with Same IP

Mark Peteren mark.petersen at markofall.com
Wed May 20 21:44:45 UTC 2020

On Wed, 2020-05-20 at 10:54 +0100, Rowland penny via samba wrote:
> On 19/05/2020 22:29, Mark Petersen via samba wrote:
> > I'm having difficulties with dhcpd updating DNS entries.
> > 
> > When I look in DNS in my Forward Lookup Zone via Windows 10 I have
> > multiple A Host records with the
> > same ip address but the names are like this:
> > 
> > Aarons-iPad Host(A) static
> > Aarons-iPadCNF:134dd19a-e0fd-4230-8108-40b4ae3328d9 Host(A)
> > static
> > Aarons-iPadCNF:156181c7-c420-409d-ab88-40c56f6b1c88 Host(A)
> > static
> The 'CNF' is short for 'collision', multiple things are trying to
> update 
> the record at the same time, first one wins, the rest get marked
> with 
> the 'CNF'.
> > Also,note that on Ubuntu 18.04 aarch64, isc-dhcp-server runs as
> > dhcpd:dhcpd
> I just found out that Debian 10 now uses 'dhcpd' as well ;-)
> > This seems to be happening with iphone/ipads (wireless) but also HP
> > printers that are all wired.
> It looks like your clients are trying to update their own records,
> you 
> only need the script if some or all of your clients cannot update
> their 
> own records, but, if you use the script, you must stop the clients
> from 
> trying to update their own records.
> Rowland

Thanks for the response.

I had the script running on both of the dhcp servers (they are setup
with failover), and I had a lot of thses CNF entries in DNS.

So as a test, I removed the script from fddc11 and the problem with all
of the extra DNS entries has stopped. Hosts are showing up in both DNS
servers as I had hoped. I will run like this for a while and see how it


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