How to push DNS settings to VPN clients in Windows Server 2012R2?

Question

I have configured L2TP VPN service in a Windows Server 2012R2 box. The service is totally fine for Windows and Linux clients but it does not work for macOS/iOS since DNS setting is not pushed to clients.

For instance, if a Mac is connected to the VPN, its /etc/resolv.conf will be gone unless an additional DNS is manually configured for the VPN. But on one hand this is kinda troublesome, on the other hand DNS setting is not available in iOS. Consequently macOS/iOS clients cannot resolve any domain names without additional configuration.

Based on https://support.microsoft.com/en-us/help/232703/how-to-use-dhcp-to-provide-routing-and-remote-access-clients-with-addi, does it mean that in Windows Server, if I'd like to push DNS settings to clients, even if I just want clients to use e.g. 8.8.8.8, I still need to set up the whole stack of DNS server and DHCP server?

https://community.spiceworks.com/topic/302769-incorrect-dns-server-on-vpn-client-rras-server-2012 says that DNS can be configured in Routing and Remote Access - IPv4 - DHCP Relay Agent but it did not work in my case and frankly I don't think it's the right place for DNS settings.

I do not need any complex services e.g. internal domain name resolution and I just want to push 8.8.8.8 to VPN clients. How can it be achieved? Thanks.

Answer 1

https://social.technet.microsoft.com/Forums/windows/en-US/17d2d49e-7476-41aa-b49a-e4b505f54da9/windows-2008-r2-isnt-giving-clients-a-connection-specific-dns-suffix?forum=winserverNIS explained how things work in Windows quite well.

So actually RRAS takes the DNS settings of the server itself and push them to VPN clients. But since my box has three virtual NICs, although only one of them is used, I have to configure DNS for all of them.