This is probably a bug,
The clients are getting an ip from 20.0/24, and it works perfectly fine.
Just from this router, where the interfaces are in VRF, im not able to ping the domain name.
The topology is simple.
ISP—>R20—>LAN
Most likely due to that the DNS-service that is /ip/dns in Mikrotik have broken VRF support. So it currently only work for VRF=main.
It was supposed to have been added in 7.15 stable but the quality assurance over at Mikrotik have work to do (its still broken in 7.15.2 stable and 7.16beta3)…
I have created a support task about this last week but still no reply from Mikrotik and here is a forumpost about this:
http://forum.mikrotik.com/t/vrf-support-for-dns-is-broken/177049/1