31. What is the minimum number of wires needed to send data over a serial communication link layer?

A. 1
B. 2
C. 4
D. 6
E. none of the above

32. The _____ layer is the layer closest to the transmission medium.

A. transport
B. network
C. data link
D. physical
E. None of the above

33. What is the name of the device that connects two computers by means of a telephone line?

A. Tape
B. modem
C. bus
D. cable
E. None of the above

34. What is the main difference between DDCMP and SDLG?

A. DDCMP does not need special hardware to final the beginning of a message.
B. DDCMP has a message header
C. SDLC has a IP address
D. SDLC does not use CRC
E. None of the above

35. On a class B network, how many subnets are available with a subnet mask of 248?

A. 2
B. 6
C. 30
D. 62
E. 126