Patent ID: 8214537

Claim:
A domain name system comprising: a DDNS server having assigned a non-static global IP address; and a DDNS client also having assigned another non-static global IP address, wherein the DDNS server comprises: a DDNS client information registration portion that registers DDNS client information indicating a relationship between a domain name of the DDNS client and the non-static global IP address of the DDNS client; a responding portion that, in response to a request for resolving a name from the DDNS client, extracts the corresponding non-static global IP address from the DDNS client information and responds to the DDNS client; and a DDNS server information notification portion that, at a time when the non-static global IP address of the DDNS server is updated or at a predetermined scheduled time, notifies DDNS server information, which includes the non-static global IP address of the DDNS server, to the DDNS client registered by the DDNS client information registration portion, wherein the DDNS server information notification portion comprises: a transmission portion that transmits an authentication message, including transmission source address information, to the DDNS client; and an authentication data transmission/reception portion that transmits/receives authentication data to/from the DDNS client, wherein the DDNS client comprises: a DDNS server information registration portion that, when the DDNS server information notification portion notifies the DDNS client, registers the non-static global IP address of the DDNS server included in the DDNS server information, wherein the DDNS server information registration portion comprises: a reception portion that receives the authentication message; and a DDNS server authentication portion that transmits/receives the authentication data to/from the DDNS server and authenticates the DDNS server, wherein the DDNS server authentication portion comprises an authentication data generation and transmission portion that receives the authentication message, generates the authentication data and transmits the authentication data to the DDNS server; and a DDNS client information notification portion notifying the relationship between the domain name of the DDNS client and the non-static global IP address of the DDNS client to the DDNS server, wherein the authentication data transmission/reception portion generates a first hash value using the authentication data received from the DDNS client and an encrypted key, and transmits the first hash value to the DDNS client, and wherein the DDNS server authentication portion generates a second hash value using the authentication data and the encryption key, and compares the second hash value and the first hash value received from the DDNS server.