1. DNS (Domain Naming System)
2. HTTP(Hypertext Transfer Protocol)
4. FTP (File Transfer Protocol),
5. TFTP (Trivial File Transfer Protocol),
6. SNMP (Simple Network Management Protocol)
7. SMTP (Simple Mail Transfer Protocol)
8. DHCP(Dynamic Host Configuration Protocol)
9. TCP (Transmission Control Protocol)
10. UDP (User Datagram Protocol)
11. IP (Internet Protocol)
12. ICMP (Internet Control Message Protocol)
13. ARP (Address Resolution Protocol)
14. RARP (Reverse Address Resolution Protocol)
15. IGMP (Internet Group Management Protocol).
16. Ethernet, Token Ring, FDDI, X.25, Frame Relay
FTP working FTP (File Transfer Protocol) is a high-level (application layer) protocol is an interface for any user of the internet to transfer files. The user requests the FTP to either retrieve from or upload a file to a remote server. FTP presents the user with a prompt and allows entering of various commands for accessing and downloading files that are physically exist on a remote computer. After invoking an FTP application, the user identifies a remote computer and instructs FTP to establish a connection with it. FTP contacts the remote computer using TCP/IP software. Once the connection is established, the user can choose to download a file from the remote computer, or an send file to be stored on the remote computer.
FTP uses two connections between a client and a server. One connection is used for the actual file’s data transfer and the other is used for control information (commands and responses). FTP uses two well-known TCP ports: port 21 is used for the control connection and port 20 is used for the data connection.