NAT64 is a translator that allows IPv6 hosts to communicate with IPv4 servers. It is a stateless translator, which means that it does not maintain any state information about the translations that it performs. This makes NAT64 very efficient and scalable.
NAT64 can be configured on both Tier-0 and Tier-1 gateways in NSX. However, the Tier-1 gateway must be configured in active-standby mode in order to use NAT64. This is because NAT64 needs to be able to maintain a consistent mapping of IPv6 addresses to IPv4 addresses, even if the active Tier-1 gateway fails.