DDNS TSIG key

[#1]

Hello everybody, 

I have a question about the DDNS to update an external zone via TSIG key.

I have two DDNS configured for my DHCP:

- One TSIG key for my internal zone

- One TSIG key to update a external zone located in the Infoblox of my client.

When the PC has finished the DHCP process, the A and TXT record are created correctly to the external authoritative zone.

But the PTR record is created in the reverse zone in my Infoblox. But this record has to be in the reverse zone in the Infoblox of my client. 

Can you give me advise to understand this comportment of Infoblox ?

[#2]

Quite a bit to unpack here:

1) Internal Zone is hosted on Infoblox or Microsoft?

2) DHCP is Infoblox or Microsoft?

3) The DHCP server is doing the DDNS update against the DNS servers?

4) What DNS server does the DHCP server use for recursion?

5) Assuming it is all Infoblox, your Infoblox appliances are on a seperate Grid to your customer's Infoblox appliances?

I'm guessing that the DHCP server is asking its recursive DNS server what the SOA record is for the PTR zone and is getting your DNS server IP instead of the customer's DNS server.