Explanation:
X.25 is an ITU-T standard protocol suite for packet switched wide area network (WAN) communication.X.25 is a packet switching technology which uses carrier switch to provide connectivity for many different networks.
For your exam you should know below information about WAN Technologies:
The following answers are incorrect:
Point-to-point protocol – PPP (Point-to-Point Protocol) is a protocol for communication between two computers using a serial interface, typically a personal computer connected by phone line to a server.
Frame Relay – The Frame relay cloud is the collection of DCE that provides that provides switching and data communication functionality. Frame relay is any to any service.
ISDN -Enables data, voice and other types of traffic to travel over a medium in a digital manner previously used only for analog voice transmission. Same copper telephone wire is used. Provide digital point-to-point circuit switching medium.
Reference:
CISA review manual 2014 page number 266