[[["容易理解","easyToUnderstand","thumb-up"],["確實解決了我的問題","solvedMyProblem","thumb-up"],["其他","otherUp","thumb-up"]],[["難以理解","hardToUnderstand","thumb-down"],["資訊或程式碼範例有誤","incorrectInformationOrSampleCode","thumb-down"],["缺少我需要的資訊/範例","missingTheInformationSamplesINeed","thumb-down"],["翻譯問題","translationIssue","thumb-down"],["其他","otherDown","thumb-down"]],["上次更新時間：2025-09-05 (世界標準時間)。"],[],[],null,["# DNS64 and NAT64 for 6to4 connectivity\n=====================================\n\nThis page describes how Google Cloud lets you access IPv4 destinations from\nIPv6-only instances using DNS64 and NAT64.\n\nGoogle Cloud provides single-stack IPv6 support through IPv6-only subnets\nand instances. For more information about which services in Google Cloud\nsupport the IPv6-only stack type, see\n[IPv6 Support in Google Cloud](/vpc/docs/ipv6-support).\n\nYour IPv6-only workloads might still require access to some IPv4 destinations.\nGoogle Cloud supports IPv6 to IPv4 connectivity through [DNS64](#dns64)\nand [NAT64](#nat64).\n\nCreating IPv6-only subnets and instances and configuring DNS64 and NAT64 lets\nyou connect your IPv6-only workloads in Google Cloud to external IPv4-only\nworkloads on the internet.\n\nYou can configure DNS64 and NAT64 for your IPv6-only workloads if you need to\ndo the following:\n\n- Adhere to mandates requiring a shift to IPv6 addresses without allocating IPv4 addresses.\n- Transition to IPv6-only address infrastructure in stages while maintaining access to existing IPv4 infrastructure.\n- Avoid disruptions to critical services by ensuring continued access to environments with IPv4 addresses during your transition to IPv6 addresses.\n\nLimitations\n-----------\n\nDNS64 and NAT64 provide connectivity from IPv6-only instances\nto IPv4 destinations on the internet. They don't provide connectivity to IPv4\ndestinations in VPC networks or on-premises networks.\n\nHow it works\n------------\n\nAccessing IPv4 destinations from IPv6-only instances requires that you configure\nboth DNS64 and NAT64.\n\nThe following diagram shows the configuration that lets IPv6-only instances\naccess IPv4 destinations on the internet. For more information\nabout each service, see the following sections.\n[](/static/vpc/images/64gateway.svg) You can access IPv4 destinations on the internet from IPv6-only instances by using DNS64 and NAT64 (click to enlarge).\n\n### DNS64\n\nDNS64 provides a synthesized IPv6 address for\neach IPv4 destination. Cloud DNS creates a synthesized address by\ncombining the [Well-Known Prefix\n(WKP)](https://www.rfc-editor.org/rfc/rfc6052#page-5) `64:ff9b::/96` with the 32\nbits of the destination IPv4 address.\n\nWhen an IPv6-only instance initiates a DNS request to resolve the name of an internet\ndestination that has only an IPv4 address, Cloud DNS returns the synthesized\nIPv6 address.\n\nFor more information about how DNS64 works, see\n[Cloud DNS overview](/dns/docs/overview).\n\n### NAT64\n\nPublic NAT supports network address translation (NAT) from IPv6\nto IPv4, or NAT64.\n\nWhen the request from an IPv6-only instance reaches the Cloud NAT\ngateway, the gateway does the following:\n\n- Replaces the source IPv6 address and port with one of the external IPv4 addresses and ports that are allocated to the gateway.\n- Translates the sythesized destination IPv6 address provided by Cloud DNS to the original IPv4 address.\n\nFor more information about how NAT64 works, see\n[NAT64 in Public NAT](/nat/docs/public-nat#nat64).\n\nWhat's next\n-----------\n\n- To establish connectivity from IPv6-only instances to IPv4 destinations, see [Configure IPv6-only subnets and instances with DNS64 and NAT64](/vpc/docs/connect-ipv6-to-ipv4)."]]
