DNS ( Domain Name Server )

The Domain Name Server (DNS) is a fundamental component of the Internet: it maps host names to IP addresses (and vice-versa). DNS is a host name to IP address translation service. DNS is a distributed database implemented in a hierarchy of name servers. It is an application layer protocol for message exchange between clients and servers.

도메인 네임 서버.

(1). Ask IP address for www.sejong.ac.kr to ISP DNS. If DNS have cache value, return IP address for www.sejong.ac.kr. If there is no cache value or if the Time To Live (TTL) has expired, you will go through the process of 2.

(2). First, ask IP address for www.sejong.ac.kr to Root Name Server.

(3). Root name server tells you to refer to the .net name server.

(4). Tell the .net name server to refer to the .com name server.

(5). You will be advised to refer to ns.superuser.co.kr Name Server.

(6). Check www.sejong.ac.kr's IP from the ns.superuser.co.kr Name Server.

(7). ns.superuser.co.kr name server will give the queried to DNS servers www.sejong.ac.kr's IP information.

(8). DNS notifies your PC of www.sejong.ac.kr's IP and save at cache of query results.