An intranet is sometimes contrasted to an extranet. The web server may restrict access to a private network such as a corporate intranet. Larger businesses allow users within their intranet to access public internet through firewall servers. Clients may communicate with the server remotely over an intranet or over the Internet. User surveys also improve intranet website effectiveness. Outside of business intranet user, very often simpler portals become replaced with richer mashup designs. GPRS is optimized for "bursty" data communication services, such as wireless internet/intranet, and multimedia services. NSANet stands for National Security Agency Network and is the official NSA intranet. DOSBox, unlike many other emulators, can simulate peer-to-peer or Internet/Intranet networking. The administrative entity limits use of the intranet to its authorized users. Samjiyon includes a browser with a support for the North Korean Kwangmyong intranet. An intranet structure needs key personnel committed to maintaining the intranet and keeping content current. Most access is to a government-controlled national intranet and an in-country e-mail system. Cell phones, the intranet, and the Internet are a luxury reserved for the DPRK elite. It was instrumental in establishing the university computer centre and the CUSAT Intranet.