To answer this question, you need to understand the concept of acknowledged and unacknowledged protocols.
Acknowledged protocols are network protocols that require the receiving device to send an acknowledgment back to the sender to confirm that the data has been received successfully. On the other hand, unacknowledged protocols do not require an acknowledgment to be sent back to the sender.
Let's go through each option to understand which protocol is unacknowledged:
Option A) SPX - SPX (Sequenced Packet Exchange) is a transport-layer protocol used by Novell NetWare. It is an acknowledged protocol, as it requires the receiver to send acknowledgments back to the sender. Therefore, this option is incorrect.
Option B) TCP - TCP (Transmission Control Protocol) is a widely used transport-layer protocol in computer networks. TCP is an acknowledged protocol, as it provides reliable, connection-oriented communication with acknowledgments. Therefore, this option is incorrect.
Option C) Telnet - Telnet is a network protocol used for remote access to servers or devices. It is an acknowledged protocol, as it requires the receiver to send acknowledgments back to the sender. Therefore, this option is incorrect.
Option D) UDP - UDP (User Datagram Protocol) is an example of an unacknowledged protocol. It is a lightweight transport-layer protocol that does not provide reliability or acknowledgments. UDP is often used for applications where speed and efficiency are more important than guaranteed delivery, such as streaming media or real-time communication. Therefore, this option is correct.
Option E) FTP - FTP (File Transfer Protocol) is a network protocol used for transferring files between a client and a server. FTP uses TCP as its transport protocol, which is an acknowledged protocol. Therefore, this option is incorrect.
The correct answer is Option D) UDP. UDP is an unacknowledged protocol that does not require the receiver to send acknowledgments back to the sender.