I have configured a dual stack mikrotik router and using IPv4 as well as IP v6 addresses on my upstream interface with ISP. I am not using Masqurade on my router. The router just routes the traffic. I have a host(windows 7 PC) connected to the router that has only IPv6 address. I have also configured an existing and running production DNS server with an additional interface with IP v6 address.
Now, I can browse the IPv6 URLs from the IPv6 host but I can not browse rest of internet.
Is this the behaviour to expect from a native IPv6 host with only IPv6 address? Or there is a workaround?
If you mean that an IPv6-only can’t access the IPv4 Internet then yes, that is absolutely expected. You’d need something like NAT64 or NAT-PT to translate protocols between IPv6 and IPv4. RouterOS cannot do that for you currently.
Also, the workaround is trivial: dual stack the host. It’ll prefer IPv6 and use IPv6 resources when available, and use IPv4 otherwise. It’s a good thing that ISPs are making IPv6 available (I wish my home ISP did) - the next step is for more content providers to offer IPv6 resources. However, someone has to start somewhere. If no ISPs are offering IPv6 connectivity, there’s no reason for content providers to offer IPv6 content. The reverse is also true, so you should applaud your ISP for breaking that feedback loop.