Domain Name System is a computer server that contains database of public IP addresses and thier respected hostnames and also sometimes respected to resolve, or translate those common names to IP addresses as requested. DSN servers is basically run special software and communicate with each other with the help of special protocols.

File Transfer Protocols it is basically used protocols to transfer/exchange files over the internet. FTP uses the internet's TCP/IP protocols to enable data transfer and also uses a client-server architecture, often secured with SSL/TLS (Secure Socket Layer/Transport Socket Layer). FTP promotes sharing of files through remote computers with reliable and efficient data transfer. FTP clients will connect to the FTP sever on port 21. This connection is called the Control Connection or Command Connection.