問題一覧
1
Presentation layer is responsible for:
Translation of one code to another
2
Digital data that is not being used to carry characters is called:
binary data
3
Which is not a common LAN medium?
twin lead
4
Cross cable can be used to connect
PC and router
5
Straight through cable can be used to connect
none of these
6
In asynch trans, the tx and rx are:
frame-by-frame sychronized using start and stop bits
7
10baseT cable typically uses:
twisted pair cable
8
Small telephone switching system that can be used as a LAN is called a
PBX
9
In asynch trans, the time between consecutive frames is:
not a set length
10
Bluetooth version ______ has a data rate of 3Mbps
2
11
medium that least susceptible to noise
fiber optic cable
12
In snch trans, the frames are:
much longer than asynch frames
13
Which medium most widely used in LANs
twisted pair
14
Classs of IP address 4.5.6.7
Class A
15
Synch trans is used bec
no start and stop bits means higher efficiency
16
In synch trans, the receiver "synchs-up" with the transmitter by using:
the data bits
17
The 1000BASE-LX has a data rate equal to
1000 Mbps
18
To maintain synchronzation in synch trans
long strings of 1s and 0s must not be allowed
19
HDLC
is a bit oriented protocol
20
Bluetooth version ____ has a data rate of 24 Mbps
3.0 + HS
21
In ___ transmission, the channel capacity is shared by both communicating devices at all times
full duplex
22
Ff are disadvantages of digital signal, except
noise immunity
23
The use of flags in SDLC requires;
bit stuffing
24
A cable break in a ____ topology stops all trnasmision
bus
25
A straight through cable can be used to convert
router and switch
26
ARQ is used to
correct bit errors
27
WIMAX has an IEEE standard of
802.16
28
Which organization has authority ovrt interstate and international commerce in the communications field?
FCC
29
Huffan codes
allows alphanumeric data to be compressed
30
The internet model consist of ___ layers
five
31
run-lenght encoding is used to
compress data
32
Process-to-procss delivery of the entire messsage is the responsibility of ___ layer
transport
33
Public-key encryption
all of the above
34
UWB has a IEEE standard of:
802.15.4a
35
The ___ layer is the layer closest to the transmission medium
physical
36
The internet is
a network of networks
37
Mail services are available to network users thought the ___ layer
application
38
Most LANs
all of the above
39
As the data pocket moves from the lower to the upp layers, headers
subtracted
40
But topology
if a backbone is broken, the connection will be lost
41
Circuit switched network
each channel carries only one data stream
42
As the data packet moves from the upper to the lower layers, headers are
added
43
What is the purpose of a hub in a star topology
act as a switch
44
Synch trans does not have
all of the above
45
Star topology
it uses a central connectivity device called a hub
46
Compared to CSMA/CD systems, token passing rings are:
all of the above
47
What does line configuration means?
identifies how devices are interconnected that individual workstations are connected to
48
The key feature of star network is that individual workstations are connected to
none of the above
49
Data from a computer are ____; the local loop handles ___ signals
digital; analog
50
Which of the ff is the most reliable network topology
mesh
51
When two or more PCs try to access a baseband network cable at the same time, it is called
contention
52
Hybrid topology
it uses two or more different topologies to form a resultant topology which has many advantages
53
The two PCs send data over a baseband network cable at the same time, it is called
a collision
54
Frequency of failure and network recovery time after a failure are measures of the ___ of a network
reliability
55
One type of network that never has a collision is
token passing
56
An unauthorized user is a network ___ issue
security
57
In data comms, link means
the physical connection between devices
58
In an Ethernet based network, a switch can be used t ireduce the number of
collision
59
What does network topology means
identifies how devices are interconnected either physically or logically
60
The effect of too many collisions is
the network slows down
61
Ring topology
it uses an electronic token
62
Communication between a computer and a keyboard involves ____ transmission
simplex
63
In a network with 25 computers, which topology would require the most extensive cabling
mesh
64
Indicate the false statement, morse code
is a fixed length code
65
The access method for wireless LANs as defined by IEEE 802.11 is based on
CSMA/CA
66
Indicate the false statement, baudot code
is also known as telex code or international alphabet number 5
67
100BaseT cable uses
twisted pair copper wires
68
FHSS, DSSS, and OFDM are ___ layer specification
physical
69
The word "base" in 10BaseTt means
the cable carries baseband signals
70
If the ___ method, the sender hops from frequency to frequency a specific order
FHSS
71
Indicate the false statement, EBCDIC code
stands for extended binary coded digital interchange code
72
The reason a CSMA/C network has a minimum length for packets is
the make sure all other nodes hear a collision in progress
73
1 dit is equal to
3.32 bits
74
The reason a CSMA/C network has a maximum length for cables is
the make sure all other nodes hear a collision in progress
75
10BaseT cable typically uses
an RJ45 connector
76
Which of the following describe the sliding motion flow control?
the transmitter first transmit one frame and wait for the receiver's acknowledgement of that frame and the increase the number of frames to be transmitted until the maximum
77
Bluetooth uses ____ in the physical layer
FHSS
78
The IEEE 488 bus uses
8 bidirectional lines connected in parallel to interface up top 15 remote devices
79
A hub
sends incoming packets ou to all other terminals connected to it
80
Which of the ff is a connecting device
all of the above
81
In data communications, what are the data link control characters
they used to facilitate the orderly flow of data from the source to the destination
82
A switch
sends incoming packets out to specific ports
83
A bridge can
do all the above
84
An advantage of using a switch instead of a hub is
is reduces the number of collisions in large networks
85
Repeaters function in the ____ layers(s)
physical (MAC)
86
What is RS-449?
a general purpose 37 position and 9 position interface
87
Using one node in the network to hold all the application software is done in
client server networks
88
A ___ is actually multiport repeater
hub
89
A "thin" client is
basically, a PC with no disk drives
90
Bridges function in the ___ layer(S)
both physical (MAC) and data link
91
A repeater takes a waken or corrupted signal and ___ it
regenerates
92
Syntax is the
format of the data
93
A bridge has access to the ____ address of a station on the same network
physical (MAC)
94
In data communications, flow control means
the regulation of the rate of transmission of data frames
95
Which error detection method uses ones complement arithmetic
checksum
96
Which of the ff is a 16 bit code
Uni-code
97
Bad frames are usually detected by the
link layer
98
Which error detection method involves polynomials
CRC
99
A virtual circuit is set up by the
network
100
Which of the ff best describes a single bit errors?
a single bit is inverted per data unit