NAT64 and DNS64 are two different components of a mechanism called IPv6 transition technologies, which are used to facilitate communication between IPv6 and IPv4 networks.
NAT64 (Network Address Translation 64):
NAT64 is a mechanism that allows IPv6-only devices to communicate with IPv4-only devices by translating IPv6 packets into IPv4 packets and vice versa. It enables IPv6 hosts to access IPv4 resources and services over an IPv6 network.
Key points about NAT64:
- Address Translation: NAT64 performs address translation between IPv6 and IPv4 addresses. It translates IPv6 packets into IPv4 packets and IPv4 responses back into IPv6 packets.
- IPv6-to-IPv4 Translation: When an IPv6-only device wants to communicate with an IPv4-only device, NAT64 translates the IPv6 source address of the packet into an IPv4 address and assigns a port number. It then forwards the packet to the IPv4 destination.
- IPv4-to-IPv6 Translation: When an IPv4-only device sends a response to an IPv6-only device, NAT64 translates the IPv4 source address and port number into an IPv6 address and forwards the response to the IPv6 destination.
- Stateless Address Translation: NAT64 typically uses stateless address translation (SAT) rather than maintaining per-connection state. This simplifies the translation process and allows for better scalability.
- Prefix-Based Translation: NAT64 uses a specific IPv6 prefix (e.g., 64:ff9b::/96) for translation. This prefix is reserved for NAT64 and acts as a marker to identify packets that require translation.
- Compatibility: NAT64 allows IPv6 hosts to access IPv4 resources without requiring dual-stack (IPv4 and IPv6) support on the host itself. It enables the gradual transition from IPv4 to IPv6 by providing a bridge between the two protocols.
DNS64 (DNS IPv6-to-IPv4 Translator):
DNS64 is a mechanism that provides IPv6-only clients with access to IPv4-only resources by synthesizing AAAA (IPv6) records for IPv4-only domains. It is used in conjunction with NAT64 to enable end-to-end communication between IPv6 and IPv4 networks.
Key points about DNS64:
- DNS Response Modification: DNS64 intercepts DNS requests from IPv6-only clients and modifies the response by synthesizing AAAA records for IPv4-only domain names.
- Synthesizing IPv6 Addresses: DNS64 creates IPv6 addresses using a well-known prefix (e.g., 64:ff9b::/96) and the IPv4 address obtained from the DNS response. These synthesized IPv6 addresses are then returned to the IPv6 client.
- IPv6-Only Perspective: DNS64 provides a solution from the perspective of IPv6-only clients, allowing them to access IPv4 resources seamlessly without requiring dual-stack support or explicit configuration.
- Encouraging IPv6 Adoption: By facilitating access to IPv4 resources over an IPv6 network, DNS64 encourages the adoption of IPv6 by minimizing the impact of IPv4 address exhaustion.
Aout NAT64 and DNS64:
NAT64 (Network Address Translation 64):
- Stateless Translation: NAT64 operates in a stateless manner, which means it does not maintain per-connection state information. Each packet is translated independently based on the network and transport layer headers.
- IPv6 Address Format: NAT64 maps IPv6 addresses to IPv4 addresses using a specific address format defined by RFC 6052. It typically uses the IPv4 address as the suffix of the IPv6 address, creating a unique mapping.
- Address Mapping Algorithm: NAT64 uses an algorithm called “IPv6 prefix plus IPv4 suffix” to map IPv6 addresses to IPv4 addresses. The IPv6 prefix is a well-known prefix reserved for NAT64, and the IPv4 suffix is derived from the corresponding IPv4 address.
- Port Preservation: NAT64 aims to preserve port information whenever possible during translation. It ensures that the translated packets maintain the original source and destination port numbers, allowing for proper end-to-end communication.
- DNS ALG (Application Layer Gateway): To handle the translation of IP addresses embedded in application-layer protocols, NAT64 often includes a DNS ALG. The DNS ALG intercepts DNS responses and modifies IPv4 addresses within the response to IPv6 format before forwarding them to the requesting client.
DNS64 (DNS IPv6-to-IPv4 Translator):
- DNS Query Modification: DNS64 modifies DNS queries from IPv6-only clients to identify requests for AAAA records (IPv6 addresses) associated with IPv4-only domain names.
- Synthesized AAAA Records: When DNS64 receives a DNS query for an IPv4-only domain name, it synthesizes AAAA records by using the well-known IPv6 prefix (e.g., 64:ff9b::/96) and the corresponding IPv4 address obtained from the DNS response.
- DNS64 Cache: To improve efficiency and reduce the load on DNS servers, DNS64 may cache synthesized AAAA records. Cached records can be used to respond to subsequent queries for the same domain name without performing additional DNS lookups.
- Address Synthesis Algorithm: DNS64 applies an algorithm called “IPv6 Prefix plus IPv4 Embedded Address” to synthesize IPv6 addresses. It combines the well-known IPv6 prefix with the embedded IPv4 address obtained from DNS responses.
- Compatibility with IPv6 Transition Mechanisms: DNS64 is designed to work in conjunction with NAT64 and other IPv6 transition mechanisms. It ensures that IPv6-only clients can access IPv4-only resources transparently by providing synthesized AAAA records.
It’s important to note that NAT64 and DNS64 are often used together in the context of IPv6 transition technologies. NAT64 performs the necessary address translation between IPv6 and IPv4, while DNS64 helps in synthesizing IPv6 addresses for IPv4-only resources. Together, they enable communication between IPv6 and IPv4 networks and promote the coexistence and migration to IPv6.
