Azure VM IP reporting incorrect

Hi,

I operate an RDS platform in Azure, I've just added a new server into the subscription and it's "mostly" fine. The new VM reports itself on the right IP (10.1.19.4) and I can connect in to it fine. I can also add it to the AD's within Azure without issue.

Note: The VM's are all static IP's within vnets. No DHCP going on.

Problem is this, nslookup for the new VM reports back as 10.1.18.4 which is in use by another VM already in the subscription. That other VM works fine, and I can connect into it fine. So when trying to add the new VM into the RDS collection, it fails to find the right IP and is giving me a kerberos error.

I've tried the things I know, ipconfig /dnsflush, ipconfig /dnsregister, and I've tried scavenging stale resource records and I've checked the hosts file for anything odd (it's totally stock). No joy. There's clearly something sitting in a table/database/file somewhere, but I can't track it down.

Any suggestions would be welcomed.