CompTIA Network+ N10-006 Q151

Which of the following is the main difference between TCP and UDP?

A. TCP data flows in two directions, while UDP data flows from server to client.
B. The TCP header implements flags, while the UDP header does not.
C. The TCP header implements checksum, while the UDP header does not.
D. TCP connections can be secured by stateful firewalls, while UDP connections cannot.

Correct Answer: B
Section: Industry standards, practices, and network theory

Transmission Control Protocol (TCP) is a connection-oriented transport protocol. Connection-oriented transport protocols provide reliable transport. When a computer wants to send data to another computer, TCP will first establish a connection between the two computers. When a sending computer sends data segments, the receiving computer acknowledges receipt of the segments. If the receiving computer does not receive an expected segment, the sending computer will send it again.
User Datagram Protocol (UDP) is a connectionless transport protocol. Connectionless transport protocols provide unreliable transport. With UDP, there is no connection establishment between the sending and receiving computers. If a data segment is lost in transit, the sending computer will not know about it so it will not resend the segment.
TCP uses control messages to manage the process of contact and communication. TCP uses a set of control flags in the TCP header to indicate whether a segment is being used for control purposes or just to carry data.