Cisco CCNA mock exam questions sample test – Question 281

.Which WAN switching technology is used with ISDN?

A. packet switching
B. virtual switching
C. circuit switching
D. cell switching

Correct Answer: C

Circuit switching dynamically establishes a connection between a source and a destination. The connection cannot be used by other callers until the circuit is released. Circuit
switching is the most common technique used with the public switched telephone network (PSTN) to make phone calls. During a call, a dedicated virtual circuit is temporarily
established between the caller and receiver for the duration of the call. Once the caller or receiver hangs up the phone, the circuit is released and is made available for other users.
Packet switching is a technique popularly used for transfer of data that is not delay sensitive and does not require real-time transfer rates from a sender to a receiver. Also unlike
circuit switching which makes a fixed amount of bandwidth available for the connection (which may not be fully utilized) packet switching uses bandwidth more efficiently. With packet
switching, the data is broken into labeled packets and is transmitted using packet-switching networks.
Cell switching is used by Asynchronous Transfer Mode (ATM). ATM is an International Telecommunication Union-Telecommunications (ITU-T) standard for transmission of data,
voice, or video traffic using a fixed size frame of 53 bytes, known as cells. Of these 53 bytes, the initial five bytes are header information and the remaining 48 bytes are the payload.
These cells are transmitted over a path that may vary with each cell. It does not maintain a dedicated virtual circuit.
The term “virtual switching” is incorrect because it is not a valid WAN switching technology.
WAN Technologies
Describe WAN access connectivity options
Cisco Documentation > Internetworking Technology Handbook > Introduction to WAN Technologies > Circuit Switching