This paper proposes to implement a domain name system (DNS) module to network simulator-3 (ns-3). The ns-3 is one of the well-known Internet simulators that provides the ideal simulation environment for network research. Despite its advantages, the ns-3 is not yet possesses a module to simulate DNS, which is an essential module required for Internet-oriented simulations. To this end, this paper implements a DNS module for ns-3 according to the design notes provided in RFC 1035. Moreover, this paper presents the implementation notes of the proposed ns-3 DNS module including its class structures, protocol message structures, name server application development, and host-to-IP resolver development. The proposed ns-3 DNS module is evaluated in terms of host-to-IP mapping, recursive DNS resolution, DNS cache management, and internationalized domain name support.