Patent ID: 7558880

Claim:
A network system, comprising: a host computer; a plurality of domain name system (DNS) proxy servers in a tree structure; a dynamic DNS server; and an address translation means, wherein the plurality of DNS proxy servers register a correspondence between an actual address of the host computer and a first domain name of the host computer, wherein the dynamic DNS server is capable of dynamically changing the actual address of the host computer corresponding to a second domain name of the host computer, wherein the address translation means is configured to: generate, when the dynamic DNS server receives a registration request from the host computer, a virtual address corresponding to the actual address of the host computer to be within a range of virtual addresses that are transferred to the address translation means; transmit, when a source address of a packet transferred from the host computer is an actual address, the packet by translating the actual address to a virtual address corresponding to the actual address; transmit, when a destination address of a packet transferred from the host computer is a virtual address, the packet by translating the virtual address to an actual address corresponding to the virtual address, and wherein the dynamic DNS server is configured to: register the correspondence between the second domain name of the host computer and the generated virtual address corresponding to the actual address of the host computer as a correspondence for forward lookup and a correspondence for reverse lookup; and provide as a response, when the dynamic DNS server receives a domain name solution request which includes a reverse lookup domain name for specifying the virtual address of the host computer, and which indicates a path to reach the dynamic server via the plurality of DNS proxy servers, the second domain name corresponding to the virtual address specified within the reverse lookup domain name by checking the correspondence for the reverse lookup.