DIGI COMMS 67-134

67. In an ESS the ___ stations are part of a wired LAN.

• A. AP
• B. Server
• C. BSS
• D. All of the above

68. The purpose of echo request and echo reply is to

• A. Report errors
• B. Check node-to-node communication
• C. Check packet lifetime
• D. Find IP addresses

69. Referred as a modem that is capable of sending and receiving fax as well as data transmission

• A. Bell 212-A
• B. ARQ
• C. Fax modem
• D. Data modem

70. The bit error rate is

• A. The number of bit errors that occur for a given number of bits transmitted
• B. The most common method of referring to the quality of a digital communication system
• C. Virtually the same as the error probability
• D. All the above

71. Bit errors in data transmission are usually cause by

• A. Equipment failures
• B. Typing mistake
• C. Noise
• D. Poor S/N ratio at the receiver

72. The number of bits per sample in DS- 1 is

• A. 1
• B. 2
• C. 4
• D. 8

73. A hub:

• A. sends incoming packets out to all other terminals connected to it
• B. sends incoming packets out to specific ports
• C. cannot be used in an Ethernet-type network
• D. are more common in token-passing networks

74. Software flow control uses:

• A. XON and XOFF
• B. TD and RD
• C. RTS and CTS
• D. DSR and DCD

75. The layer is the layer closest to the transmission medium.

• A. Physical
• B. Data link
• C. Network
• D. Transport

76. The synchronous payload envelope of an STS- 1 frame contains ____.

• A. Pointers
• B. User data
• C. Overhead
• D. (b) and (c)