A method of a first DNS which can update server information in real time without necessarily using a TTL (Time To Live) by recording a network address of the first DNS, which has previously obtained server address information from a second DNS, in a notification list, by the second DNS, and transmitting the changed information from the second DNS to the first DNS recorded in the notification list when the previously obtained/requested server address changes, and updating the server address by the first DNS as provided by the second DNS. A DNS updating server address method may further include providing a first DNS with server address information corresponding to a domain, recording a network address of the first DNS in a notification list, corresponding to the domain and/or the server address information, and transmitting a changed server address information to the first DNS based on the notification list.