Dual stack is the correct IPv6 migration strategy because the existing infrastructure already supports IPv6, the company wants low operational overhead, and applications should migrate naturally using DNS. Cisco describes dual stack as running IPv4 and IPv6 simultaneously on the same infrastructure, allowing hosts and applications to use either protocol during the migration period. It does not require additional tunneling equipment, avoids encapsulation overhead, supports native IPv6 multicast, and allows application preference to follow DNS responses. ISATAP and manual tunnels introduce overlay complexity and are primarily transition mechanisms for connecting IPv6 islands over IPv4 infrastructure. A service block model may be useful for specific service insertion, but it does not provide a whole-network migration strategy. Since every current infrastructure device supports IPv6, the cleanest and most operationally straightforward model is to enable IPv6 alongside IPv4 and migrate services gradually. Reference topics: IPv6 migration, dual-stack deployment, DNS-based protocol selection, native IPv6 multicast, transition strategy design.