samba - May 2020 - Fwd: DHCP Updates to DNS - Multiple Entries with Same IP

On 21/05/2020 12:22, Derek Cramer via samba wrote:
> I had exactly the same issue with dual dhcp servers. I solved it by
> modifying the script to do conditional updates. I.e. only add the A/PTR
> entries if they are not already present.
Now that is a good idea, why didn't I think of it ;-)

I have identified a slight bug with the 'add' part, if you reboot a 
client and it releases the IP, then when the the client comes up and the 
script is run, it claims the update has failed, even though it has 
succeeded. I have a fix.

The problem with the 'failover' is down to using '128' on both
DC's,
this leads to both of them replying to requests, I will update the 
wikipage to use '255' on the primary and '0' on the secondary.
This
should lead to only one (the primary) replying unless the primary goes down.

Rowland

I think you can continue to use '128' (good for load balancing,
otherwise
255 is fine). I had the same issue, following dhcpd.conf entries fixed it
(the last entry is important):

one-lease-per-client  true;
deny                          duplicates;
ignore-client-uids      true;

And it's not a bug, it's by design as is **REQUIRED** by the RFCs.

Best regards,
Matt


On Thu, May 21, 2020 at 8:08 AM Rowland penny via samba <
samba at lists.samba.org> wrote:
> On 21/05/2020 12:22, Derek Cramer via samba wrote:
> > I had exactly the same issue with dual dhcp servers. I solved it by
> > modifying the script to do conditional updates. I.e. only add the
A/PTR
> > entries if they are not already present.
>
> Now that is a good idea, why didn't I think of it ;-)
>
> I have identified a slight bug with the 'add' part, if you reboot a
> client and it releases the IP, then when the the client comes up and the
> script is run, it claims the update has failed, even though it has
> succeeded. I have a fix.
>
> The problem with the 'failover' is down to using '128' on
both DC's,
> this leads to both of them replying to requests, I will update the
> wikipage to use '255' on the primary and '0' on the
secondary. This
> should lead to only one (the primary) replying unless the primary goes
> down.
>
> Rowland
>
>
>
> --
> To unsubscribe from this list go to the following URL and read the
> instructions:  https://lists.samba.org/mailman/options/samba
>

On 21/05/2020 21:04, Matt Savin wrote:
> I think you can continue to use '128' (good for load balancing, 
> otherwise 255 is fine). I had the same issue, following dhcpd.conf 
> entries fixed it (the last entry is important):
>
> one-lease-per-client? true;
> deny ? ? ? ? ? ? ? ? ? ? ? ?? duplicates;
> ignore-client-uids ? ?? true;
>
> And it's not a bug, it's by design as is **REQUIRED** by the RFCs.
Perhaps 'bug' was the wrong word ;-)

It is my understanding that with '128', both dhcp servers listen and 
reply to requests, with '255' only one server listens and replies.

Rowland