DNS (Domain Name Server) is the system that contains various information of domain area assigned to each of the participating entities.

For example, '.kr' domain contains 'or.kr' domain, and 'or.kr' domain contains 'kisa.or.kr' domain. In general, domain administrator manages the domain and sub-domain. The administrator of 'kisa.or.kr' can generate sub-domain like 'www.kisa.or.kr' or 'domain'kisa.or.kr'.