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