Understand the change.
Choose the right method.

IPv4 and IPv6 are different protocols.

An IPv4-only endpoint cannot simply treat an IPv6 address as a longer IPv4 address. Communication needs compatible endpoints or a deliberately selected transition mechanism. A new address alone does not establish reachability.

Begin by drawing the client, resolver, access network, routers, security controls and destination. Mark which protocol each actually supports.

Dual stack keeps both paths in view.

A dual-stack deployment supports both protocols. Check routing, DNS records, service listeners and policy for each. Observe application behaviour rather than assuming which path a client will choose.

Test administration, monitoring and incident response too. Keep a bounded pilot and a documented recovery route.

NAT64 and DNS64 solve a particular problem.

Stateful NAT64 translates traffic from IPv6 clients towards IPv4 servers. DNS64 can synthesise an IPv6 answer from an IPv4 DNS answer so a client can use that translation path.

It is not a universal solution for inbound IPv4 clients reaching an IPv6-only service. Literal IPv4 addresses and application behaviours can require additional work. Review DNSSEC validation placement and the effect of synthesised answers as part of the DNS design.

Where 464XLAT fits.

464XLAT combines stateless translation near the client with stateful translation in the network. It can provide limited IPv4 connectivity across IPv6-only access, including support for IPv4-oriented applications.

Its suitability depends on the client and access environment. It does not replace application testing or create unrestricted compatibility for every protocol.

A mapped address is not a deployed service.

An IPv4-mapped IPv6 representation such as ::ffff:192.0.2.1 has a role in software interfaces. Writing that representation does not give an IPv4 host native IPv6 connectivity or make the result a public route.

Likewise, tunnel and translation designs need routing, security and operational decisions. Do not select a mechanism merely because an online calculator prints an address.

Prove the complete experience.

• Authoritative and recursive DNS behaviour, including appropriate A and AAAA answers.
• Application listeners, routing, firewalls and necessary ICMPv6 behaviour.
• Monitoring, logs and support tools that recognise the actual protocol path.
• Failure cases, changed dependencies and a reviewed rollback.