Question: what are ipv6 dns servers?
Answer: For IPv4: 8.8. 8.8 and/or 8.8. 4.4. For IPv6: 2001:4860:4860::8888 and/or 2001:4860:4860::8844. For IPv6-only: you can use Google Public DNS64 instead of the IPv6 addresses in the previous point.