TCP & UDP are Layer4 protocols TCP provide features which are not available in UDP:: - Connection Oriented --> 3way handshake / 4way termination - Flow control --> Window size - Packets re-order --> sequence - Error recovery --> packets re-transmission if ACK is not received -Reliable Data transmission Ex protocols that use TCP: FTP / SSH / Telnet/ SMTP / HTTP/ HTTPs/ Pop3 UDP: Used mainly in Real time applications (Video// Audio) - UDP header is small , less overhead, fast data transfer - Not reliable if segment is lost no way to tell hence no retransmission - Not connection oriented, data is just sent Ex protocols that use UDP: DHCP/ TFTP/ SNMP / Syslog