You go to Network and Sharing Center, click Change Adapter Settings, right-click the connection, choose Properties, and select IPv6 to manually configure a server's IP address. Which information is NOT required in order to configure IPv6?

A subnet mask is not required when configuring a static IP address in IPv6 networking, but you do need to be aware of the subnet prefix length. That's the only difference between configuring IPv4 and IPv6. You must know the preferred DNS server's address in addition to the IPv6 address and default gateway.