Network communication system

The invention discloses a network communication system. The system comprises a domain name system DNS device, a first network address translation device, a second network address translation device and an Internet data center IDC, and the DNS device is used for responding to a domain name query request sent by an IPv4 single-stack user device, determining a protocol version of an IP address corresponding to a target domain name in the domain name query request, and sending the determined protocol version to the IPv4 single-stack user device. Determining a destination IP address according to the protocol version and the IP address; the first network address conversion equipment is used for converting an IPv4 request message sent by the user equipment into an IPv6 request message according to the mapping relation or a preset prefix; and the second network address translation equipment is used for determining a target request message by comparing whether the prefix part of the IPv6 request message is consistent