Corresponding relation obtaining method and system

The embodiment of the invention provides a corresponding relation obtaining method and system. On one hand, the corresponding relation between an entry network interconnection protocol IP address of a local domain name system (DNS) and an exit IP address of the local DNS is obtained, the corresponding relation between the exit IP address of the local DNS and a public network IP address of a client side is obtained, and then according to the corresponding relation between the entry IP address of the local DNS and the exit IP address of the local DNS, and the corresponding relation between the exit IP address of the local DNS and the public network IP address of the client side, the corresponding relation between the entry IP address of the local DNS and the public network IP address of the client side is obtained. According to the technical scheme, the corresponding relation between the public network IP address of the client side and the entry IP address of the local DNS can be collected automatically, and the collecting efficiency of the corresponding relation is improved.