Several people are disabling IPv6 support in ESXi for different reasons: because of the minimum privilege principle (if you are not using a service, why you have to keep it enabled?) or simple because they don’t want any IPv6 address in the network. On Linux and Windows systems is become very difficult disable it and Microsoft itself does not recommend disabling IPV6: ” We do not recommend that you disable IPv6 or its components, or some Windows components may not function.” (https://support.microsoft.com/en-us/kb/929852)