[Dnsmasq-discuss] override DNS server for particular hosts on IPv6

[Hamish Moffatt]

On 26/3/21 2:52 am, M. Buecher wrote:
>
> Android to my knowledge does not support DHCPv6, therefore it only 
> retrieves DNS servers via RDNSS of RAs.
> RAs are generic and not per client, therefore assigning different DNS 
> servers via RDNSS/RA is not possible.
>
> Even if dnsmasq could disable RDNSS for RAs you will still fail with 
> Android as long as it does not support DHCPv6.
>
> Only idea I have is to use a separate ULA in a separate WLAN/LAN 
> network for those devices, and for this ULA use the adblock settings 
> as defaults. 


Thanks Maddes. RDNSS was the part I was missing. This explains the 
behaviour I saw on Android (the client learned the subnet default 
server), and NetworkManager too (learned both the RDNSS-distributed DNS 
server (the subnet default server), and the overriden DHCP value).

I set up a separate VLAN/SSID with the default DNS server set to my 
other server, and everything works as expected.

I would have been happy to disable RDNSS (non-DHCP clients could just 
use the IPv4 DNS server), but that isn't possible without disabling the 
IPv6 DNS server DHCP option altogether, which the OpenWRT config 
generator does not allow unfortunately.


Hamish