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1. Given G(x) = X^5 + X^3 + X^2 + 1, what size CRC (in bits) will result?

a) 2
b) 3
c) 5
d) 8
e) None of these

2. Which BCC value below is the correct EVEN longitudinal parity for the data block {$02, $03}? The values are in hexadecimal.

a) $af
b) $01
c) $04
d) None of these

3. A group of data sent together is called a/an:

a) Block check character
b) Frame
c) Block
d) (B) or (C)
e) None of these

4. What is the meaning of the control signal NAK in an ARQ system?

a) Bad data detected; resend the data again
b) Receiver unreachable; no connection was possible
c) Too many retries in transmitting the data; abort
d) None of these

5. Which of these error detection techniques would be the most likely to detect data that has been tampered with by changing the order of the bytes?

a) Checksum
b) CRC
c) Biased Checksum
d) Longitudinal Parity
e) Lateral Parity

6. When a Hamming data receiver half-adds (exclusive-ORs) the received checkbits with the regenerated checkbits, what is the meaning of the result?

a) The count of bits in the word that were in error
b) The checksum of the all the data in the block
c) The address of the bit in error
d) None of these

7. When would a FEC system most likely be utilized?

a) When there are very large amounts of data being sent in each data block
b) When parity is being used to check the contents of each data block
c) When the receiver is expected to request the retransmission of any damaged blocks
d) None of these

8. If a terminal doesn't respond to a host poll or select command in a 3270 network, what will likely happen next?

a) The host will exclude the device on subsequent rounds; the terminal is locked out
b) The host will try communicating with the device for about 150 seconds before giving up
c) The host will skip the device and try it again on the next loop
d) None of these

9. You're troubleshooting an IBM 3270 network that seems to be locked - no communications is occuring and host has locked out all the remote terminal units. On the host modem you notice that the DCD light is steadily lit. What is likely wrong?

a) The host modem is defective and unable to receive any signal from the network
b) The host modem is stuck in transmit mode and unable to receive any signals
c) One of the remote units is stuck in transmit mode
d) None of these

10. When is it permissible for a terminal to transmit on a 3270 multidrop network?

a) Whenever the terminal's data buffer is full
b) Only in response to host commands
c) Whenever another terminal needs data from the unit
d) None of tnese

11. Where is the address contained within a 3270 message?

a) After the STX character within the message
b) Within the header
c) After the BCC
d) None of these

12. When IBM3270 is running in multidrop mode, what response does a terminal provide to a poll when it has no data for the host?

a) EOT
b) ACK0
c) ACK1
d) WACK
e) None of these

13. Why is an alternating acknowledge system used in the IBM 3270 protocol?

a) To increase the speed of communications on the network
b) To detect lost message packets
c) To improve error detection quality on individual packets
d) None of these

14. If a terminal is busy or has a full memory buffer when it is selected by a host, how might it respond to a select command in the IBM 3270 protocol?

a) ACK0
b) ACK1
c) WACK
d) RVI
e) None of these

15. A primary unit sends the following frame. What will probably happen next on the network?

RR A=02 P/F=1 NR=03

a) Secondary unit 03 will stop responding to any further host requests
b) All units on the network will get ready to receive the subsequent broadcast data frame(s)
c) Secondary unit 02 will respond with a frame for the host
d) None of the above

16. The NR/NS acknowledgment system of HDLC could be classified as functioning in what OSI model layer?

a) 1 - Physical
b) 2 - Data Link
c) 3 - Network
d) 4 - Transport
e) 5 - Session
f) 6 - Presentation
g) 7 - Application

17. In the HDLC protocol, what pattern marks the beginning and end of data frames?

a) FLAG
b) BCC
c) FCS
d) LRC
e) None of these

18. The following HDLC exchange occured on a network:

RR A=7E P/F=1 NR=07

                    I A=7E P/F=0 NR=06 NS=07
                    I A=7E P/F=1 NR=06 NS=00

What will the host respond with if all the frames have been correctly received (assuming that the host doesn't have any data to send to unit $7E.)

a) RR A=7E P/F = 1 NR=02
b) RNR A=7E P/F = 1 NR=07
c) RR A=7E P/F = 0 NR=01
d) None of these

19. The following HDLC exchange occured on a network:

RR A=43 P/F=1 NR=07

                    I A=43 P/F=0 NR=06 NS=07
                    I A=43 P/F=0 NR=06 NS=00
                    I A=43 P/F=0 NR=06 NS=01
                    I A=43 P/F=1 NR=06 NS=02
RR A=43 P/F=1 NR=00

What will happen next on the network?

a) The primary unit will service the next terminal in the poll list
b) Secondary unit 43 will transmit frames 0,1,2
c) Secondary unit 43 will transmit only frame 0
d) The host will lock secondary unit 43 off the network, no longer polling it

20. Within the zero-stuffed area of an HDLC data frame, how will the data pattern %1111 1111 be represented?

a) 1111 10101
b) 1111 10111
c) 1010 11101
d) 0001 11110
e) None of these

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