Method and apparatus for handling IPv4 DNS PTR queries across IPv4 and IPv6 networks

摘要

Disclosed are methods and apparatus for efficiently and reliably handling DNS (domain name service) PTR (pointer) queries and replies across IPv4 and IPv6 networks. In general terms, an IPv4 DNS PTR query which is sent by an IPv4 device to an IPv6 DNS Server is intercepted or received, for example, by a network device configured with NAT-PT and DNS-ALG. The received IPv4 DNS PTR query is then translated into two different types of IPv6 DNS PTR queries: a query having an “IP6.INT” string and a query having an “IP6.ARPA” string. Both types of IPv6 queries are then sent to the IPv6 destination DNS Server. Whether the DNS sends an IP6.ARPA or an IP6.INT type reply or both types of replies back, a valid reply is identified (if present) and then translated before reaching the IPv4 device.