An address resolution protocol method of a router device comprising steps of: (a) Proving an Internet domain to connect a plurality of computers and a router device. (b) Accepting an address resolution protocol due to the router device, and the address resolution protocol has a sender Internet protocol address (SIPA) and a target Internet protocol address (TIPA). (c) Comparing the SIPA to have the internal domain. (d) Sending to an Internet resolution protocol (IRP) within the Domain Name of Internet network, and to send the IRP to compare with the internal control protocol address. (e) Corresponding with the SIPA of the internet address; renewing the one of the data of the location of the address due to the router device; the SIPA not to correspond with the data of the internet address; the router device to save the SIPA.