1. How many OSI layers are covered in the X.25 standard?
(A) Two (B) Three
(C) Seven (D) Six
2. Layer one of the OSI model is .................
(A) physical layer (B) link layer
(C) transport layer (D) internet work layer
3. The X.25 standard specifies a ...............
(A) technique for start-stop data
(B) technique for dial access
(C) DTE/DCE interface
(D) None of above
4. Which of the following communication modes support two-way traffic but in only one direction at a time?
(A) simplex (B) half duplex
(C) three-quarters duplex (D) all of the above
5. Which of the following might be used by a company to satisfy its growing communications needs?
(A) front end processor (B) multiplexer
(C) controller (D) All of the above
6. What is the number of separate protocol layers at the serial interface gateway specified by the X.25 standard?
(A) 4 (B) 2
(C) 6 (D) 3
7. The interactive transmission of data within a time sharing system may be best suited to
(A) simplex lines (B) half-duplex lines
(C) full duplex lines (D) None of these
8. Which of the following is considered a broad band communication channel?
(A) coaxial cable (B) fiber optics cable
(C) microwave circuits (D) all of the above
9. Which of the following is not a transmission medium?
(A) telephone lines (B) coaxial cables
(C) modem (D) microwave systems
10. Which of the following does not allow multiple uses or devices to share one communication line?
(A) doubleplexer (B) multiplexer
(C) concentrator (D) controller