Architecture that includes optimizations for “Bump-in-the-API” (BIA) as employed for multi-stack hosts. These optimizations reduce the limitations imposed by the existing translation technologies by simplifying the implementation and addressing possible compatibility issues. More specifically, the architecture discloses optimizations that use a preconfigured NAT64 prefix for mapping of NAT64 IPv6 addresses in the prefix subnet to IPv4 addresses, without a mapping table (stateless), use configuration information for enabling API translation per application (resolves possible compatibility issues), and use a local IPv4 socket and a data pump to reduce the number of translated API calls.