Background: I'm essentially re-creating Back To My Mac.
I have a VPN set-up on my VPS, handing out addresses in the
10.x.y.0/24 range, with BIND running and accessible at
There's a zone named
xyz with updates enabled. The SOA/NS records for
xyz indicate a globally-resolvable name,
dns.xyz-public.com, which resolves to
10.x.y.1. (i.e. the address can only contacted within the VPN.)
When I configure Dynamic DNS (through Sharing: "Use dynamic global hostname"), I set my hostname to
mylaptop.xyz, set credentials, and voilà;
mylaptop appears in the zone!
... only, it's added with the IP address as seen by the public internet, not as seen in the VPN. I had assumed that, given the DNS update was happening via a local address, the IP address that corresponded would be used, but it would appear OS X is determining its own public IP address itself before publishing it to DNS.
Is there any way to work around this?