TCP

The Transmission Control Protocol (TCP) is a connection-oriented protocol for communications. It breaks down the data into small bundles and afterward reassembles the bundles into the original message on the opposite end.

Three-way handshake

The TCP model uses a three-way handshake to establish connection.

• Sender sends a segment with a SYN (synchronize sequence number) which informs the recipient that the client is likely to start communication.

• Recipient responds with SYN-ACK to the client request. Acknowledgement (ACK) signifies the response of the segment it received, and SYN signifies with what sequence number it is likely to start the segments with.

• Finally, sender sends ACK in response to the recipient, and they both establish a reliable connection with which they will start the actual data transfer.

  

UDP

The User Datagram Protocol is an unreliable and connectionless protocol. Unlike TCP, UDP does not guarantee delivery, order, or error checking, making it a lightweight and efficient option for certain types of data transmission such as video conferencing.

• Used for simple request-response communication when the size of data is less and hence there is lesser concern about flow and error control.
• It is a suitable protocol for multicasting as UDP supports packet switching.
• Normally used for real-time applications which can not tolerate uneven delays between sections of a received message.
• DNS (Domain Name System) also uses UDP for its query/response messages. DNS queries are typically small and require a quick response time, making UDP a suitable protocol for this application.
• DHCP (Dynamic Host Configuration Protocol) uses UDP to dynamically assign IP addresses to devices on a network. DHCP messages are typically small, and the delay caused by packet loss or retransmission is generally not critical for this application.