Certified Information Systems Security Professional (CISSP) Practice Exam 2025 – All-in-One Guide to Mastering Your Certification!

X.25 is classified as an older packet-switched WAN (Wide Area Network) protocol that was widely used before the emergence of modern networking technologies such as frame relay and internet protocols. Developed in the 1970s, X.25 works by breaking down data into packets and sending them through a network of interconnected nodes. This approach allows for more efficient use of network resources because multiple packets from different sources can share the same network links.

The protocol provides a means for establishing virtual circuits and offers features such as error correction and flow control, which are essential for ensuring reliable data transmission over long distances. Its design creates a level of abstraction from the physical network, thus allowing data to be sent reliably, even over unreliable physical connections.

The other options refer to more contemporary networking concepts or protocols that do not accurately describe X.25. For instance, unicast protocols focus on one-to-one communication, while next-gen protocols and high-speed local area protocols pertain to technologies that leverage advances in networking such as high-speed connections and efficient local area networking capabilities, which are not characteristics of X.25.