B low-altitude satellite
C fiber optics D wireless LAN
1．The ( ) is a worldwide computer network, that is, a network that interconnects millions
of
computing
devices
throughout the world. ppt3 A public 4．The units of data exchanged by a
link-layer protocol are called ( ).
Internet A Frames
B Intranet
C switch net D television net
2．Which kind of media is not a guided media ( )
A twisted-pair copper
wire
B a coaxial cable C fiber optics
D digital satellite channel
3．Which kind of media is a guided media
( )
A geostationary satellite
B Segments
C Datagrams D bit streams
5．Which of the following option belongs to the circuit-switched networks ( )
A FDM
B TDM
C VC networks
D both A and B
6．( )makes sure that neither side of a connection overwhelms the other side by sending too many packets too fast. A Reliable data transfer
B Flow control
C Congestion control
packet-switched virtual-circuit
networks, networks
and are
circuit-switched networks.
D Handshaking procedure
C datagram networks use destination
7．( ) means that the switch must receive the entire packet before it can begin addresses and virtual-circuit networks use VC. numbers to forward packets to transmit the first bit of the packet onto the outbound link.
A Store-and-forward transmission
B FDM
C End-to-end connection
D TDM
8．Datagram networks and virtual-circuit networks differ in that ( ). A datagram networks are circuit-switched networks, and virtual-circuit
networks
are
packet-switched networks. B datagram
networks
are
toward their destination.
D datagram networks use VC. numbers
and virtual-circuit networks use destination addresses to forward packets toward their destination.
9．In the following options, which one is
not a guided media ( )
A twisted-pair
wire
B fiber optics
C coaxial cable D satellite
10．Processing delay does not include the
time to ( ).
A examine the packet’s header
packets known as ( ) from one host to B wait to transmit the packet onto the link
C determine where to direct the packet D check bit-error in the packet
11．In the following four descriptions, which one is correct ( )
A The traffic intensity must be greater than 1.
B The fraction of lost packets increases as the traffic intensity decreases.
C If the traffic intensity is close to zero, the average queuing delay will be close to zero.
D If the traffic intensity is close to one, the average queuing delay will be close to one.
12．The Internet’s network layer is
responsible for moving network-layer
another.
A frame B datagram
C segment D message
13．The protocols of various layers are called ( ).
A the
protocol
stack
B TCP/IP
C ISP D network protocol
14．There are two classes of
packet-switched networks: ( ) networks and
virtual-circuit
networks.
A datagram
B circuit-switched
C television
D telephone
15．Access networks can be loosely
18．In the Internet, the equivalent concept to end systems is ( ).
A hosts classified into three categories: residential access, company access and ( ) access.
A cabled B wireless
C campus D city area Question 16～17
Suppose, a is the average rate at which packets arrive at the queue, R is the transmission rate, and all packets consist of L bits, then the traffic intensity is ( 16 ), and it should no greater than ( 17 ).
16．
A LR／a B La／R
C Ra／L
D LR／a
17．A 2
B 1
C 0
D -1
B servers
C clients D routers
19．In the Internet, end systems are connected together by ( ).
A copper wire
B coaxial cable
C communication links D fiber optics
20．End systems access to the Internet
through its ( ).
A modems
B protocols
C ISP
D sockets
21．End systems, packet switches, and other
pieces of the Internet, run ( ) that control the sending and receiving of information within the Internet. D WAN
23．The internet allows ( ) running on its
end systems to exchange data with each other. A clients
applications
A programs
B processes
C applications
D protocols
22．There are many private networks, such
as many corporate and government
networks, whose hosts cannot exchange
messages with hosts outside of the private network. These private networks are often referred to as ( ).
A internets B LAN
C intranets
B server applications C P2P
applications
D distributed applications
24．The Internet provides two services to
its distributed applications: a
connectionless unreliable service and
() service.
A flow control
B connection-oriented reliable C congestion control
D TCP
25．It defines the format and the order of
messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or receipt of a message or other event. The sentence describes ( ).
D the transmission signals are digital signals or analog signals 27．In the following options, which is defined in protocol ( ) A the
actions
taken
on
the
A Internet B protocol
C intranet D network
26．In the following options, which does not define in protocol ( )
A the format of messages exchanged between two or more communicating entities
B the order of messages exchanged between two or more communicating entities
C the actions taken on the
transmission of a message or other event
transmission and/or receipt of a message or other event
B the objects exchanged between communicating entities
C the content in the exchanged messages
D the location of the hosts
28．In the following options, which does not belong to the network edge ( )
A end systems B routers
C clients
D servers
29．In the following options, which belongs
to the network core ( )
A end systems B routers
B congestion-control C reliable
data transfer
D connection-oriented service
C clients
32．It makes sure that neither side of a
D servers
30．In the following options, which is not
the bundled with the Internet’s connection-oriented service ( )
A reliable data
transfer
B guarantee of the transmission timeC flow control
D congestion-control
31．An application can rely on the
connection to deliver all of its data without error and in the proper order. The sentence describes ( ). A flow control
connection overwhelms the other side by sending too many packets too fast. The sentence describes ( ). A flow
control
B congestion-control
C connection-oriented service
D reliable data transfer
33．It helps prevent the Internet from
entering a state of gridlock. When a packet switch becomes congested, its buffers can overflow and packet loss can occur. The sentence describes ( ).
A flow
control
36．The Internet’s connectionless service
B congestion-control C connection-oriented
is called ( ).
service A TCP
D reliable data transfer
34．The Internet’s connection-oriented service has a name, it is ( ).
A TCP
B UDP
C TCP/IP
D IP
35．In the following options, which service does not be provided to an application by TCP( )
A reliable transport
B flow control C video conferencing
D congestion control
B UDP
C TCP/IP
D IP
37．In the following options, which does not use TCP( )
A SMTP
B internet telephone
C FTP
D HTTP
38．In the following options, which does
not use UDP( )
A Internet
phone
B video conferencing
C streaming
multimedia
D telnet
39．There are two fundamental approaches
to building a network core, ( ) and packet switching. A electrical
41．In ( ) networks, the resources are not
reserved; a session’s messages use the resources on demand, and as a consequence, may have to wait for access to communication link.
current
switching
A packet-switched B circuit switching
C data switching
D message switching
40．In ( ) networks, the resources needed
along a path to provide for communication between the end system are reserved for the duration of the communication session.
A packet-switched B data-switched
C circuit-switched
D message-switched
B data-switched
C circuit-switched
D message-switched
42．In a circuit-switched network, if each
link has n circuits, for each link used by the end-to-end connection, the connection gets ( ) of the link’s
bandwidth for the duration of the
connection. A a
fraction
1/n
B all
C 1/2
D n times
43．For ( ), the transmission rate of a
circuit is equal to the frame rate according to host destination
addresses is called ( ) network. A circuit-switched multiplied by the number of bits in a slot.
A CDMA
B packet-switched network
C TDM D FDM
44．( ) means that the switch must receive
the entire packet before it can begin to transmit the first bit of the packet onto the outbound link.
A Queuing delay
B Store-and-forward transmission C Packet loss
D Propagation
45．The network that forwards packets
B packet-switched
C virtual-circuit
D datagram
46．The network that forwards packets
according to virtual-circuit numbers is called ( ) network.
A circuit-switched B packet-switched
C virtual-circuit
D datagram
47．In the following entries, which is not a kind of access network( )
A residential access
B company access C wireless
D none of the above
access 49．The time required to examine the
packet’s header and determine where
D local access
48．Suppose there is exactly one packet
to direct the packet is part of the ( ). switch between a sending host and a receiving host. The transmission rates between the sending host and the switch and between the switch and the receiving host are R1 and R2, respectively. Assuming that the switch uses store-and-forward packet switching, what is the total end-to-end delay to send a packet of length L (Ignore queuing delay, propagation delay, and processing delay.) ( )
A L/R1＋L/R2 B L/R1
C L/R2
A queuing delay
B processing delay C propagation delay
D transmission delay
50．The time required to propagate from the
beginning of the link to the next router is ( ). A queuing delay
B processing delay C propagation
delay
D transmission delay
51．Consider sending a packet of 3000bits
over a path of 5 links. Each link transmits at 1000bps. Queuing delays, propagation
does it take to send the packet
Solu
delay and processing delay are negligible. (6 points) (1).Suppose
the
network
is
a
tion: (1). t=5*(3000+500)/1000+=
(2). t=5*(3000+200)/1000=16s
packet-switched virtual circuit network. VC setup time is seconds. Suppose the sending layers add a total of 500 bits of header to each packet. How long does it take to send the file from source to destination (2).Suppose
the
network
is
a
packet-switched datagram network and a connectionless service is used. Now suppose each packet has 200 bits of header. How long does it take to send the file (3).Suppose that the network is a circuit-switched network. Further suppose that the transmission rate of the circuit between source and destination is 200bps. Assuming setup time and 200 bits of header appended to the packet, how long
(3). t=(3000+200)/200+=
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