use alias to specify DNS server

[defaultuserfoo]

I need to  use an alias to specify a name server address for clients on a VLAN.

The address of the name server is an IPv6 address on another VLAN.  It's assigned to the server through DHCPv6.  I have created an alias for the server as a dynamic IPv6 host because the IPv6 prefix may change at any time.  So the only way to somehow specify the address of the DNS server seems to be using the alias.

Unfortunately, in the DHCPv6 configuration of the interface the client is connected to, the web interface won't let me use the alias to specify a name server but says "A valid IPv6 address must be specified for the primary/secondary DNS servers."

So how am I supposed to specify a valid IPv6 address for DNS server?


I've given the DNS server also the address fd53::11/16 on one of its interfaces.  I could use that as address for the DNS server for the clients, but opnsense does not have an interface in that network.  Since the interface for the VLAN the clients are in is tracking the WAN interface to get IPv6 addresses, there doesn't seem to be any way to put an additional IPv6 address on that interface, and the DNS server remains unreachable.

How can I give interfaces that are tracking the WAN interface for IPv6 addresses additional addresses?

I guess I could add another VLAN and give opnsense another interface to make the DNS server reachable, but that seems like a rather convoluted solution and overkill for a problem that should be easy to solve.