传输层小测题

Quizzes for Transport Layer
Department of Computer Science
1. One of the main duties of the transport layer is to provide ___________ communication.
A) node-to-node
B) host-to-host
C) process-to-process
D) None of the choices are correct
2. A client program normally uses ___________ port number. A server program normally uses
_________ port number.
A) a well-known; an ephemeral
B) an ephemeral; a well-known
C) a private; a well-known
D) None of the choices are correct
3. A socket address is a combination of ________ .
A) A MAC address and a logical address
B) A MAC address and a port number
C) a user-specific address and a logical address
D) None of the choices are correct
4. ____________ means accepting items from more than one source. __________________
means delivering items to more than one source.
A) Demultiplexing; Multiplexing
B) Multiplexing; Demultiplexing
C) Encapsulation; Decapsulation
D) Pulling; Pushing
5. ______ means the producer delivers the items when they are produced. ______ means the
consumer takes the items when it is ready to do so.
A) Pushing; pulling
B) Pulling; pushing
C) Forwarding; accepting
D) None of the choices are correct
6. In the stop-and-wait protocol, the maximum send window size is _____ and the maximum
receive window size is ______ where m is the number of bits in the sequence.
A) 1； 1
B) 2m; -1
C) 1； 2m
D) 2m; 2m
7. In the Go-Back-N protocol, the maximum send window size is __________ and the maximum
receive window size is ______ , where m is related to the number of bits in the sequence
number.
A) 1; 1
B) 1; 2m
C) 2m-1；1
D ) ?m T ・？m -1
In the selective-repeat protocol, the maximum send window size is _ and the maximum
receive window size is ______ , where m is the number of bits in the sequence.
9. UDP is a ______________ transport protocol.
A) connectionless, reliable
B) connection-oriented, unreliable
C) connectionless, unreliable
D) None of the choices are correct
10. UDP is an acronym for ______ . A) User Delivery Protocol
B) User Datagram Procedure
C) User Datagram Protocol
D) None of the choices are correct
11. At the transport layer, to define the processes, we need two identifiers called ___________
A) logical addresses
B) physical addresses
C) port addresses
D) None of the choices are correct
12. The ports ranging from 0 to 1,023 are called the __________ ports. The ports ranging from
1,024 to 49,151 are called __________ ports. The ports ranging from 49,152 to 65,535 are called the __________ ports.
A) well-known; registered; dynamic or private
B) registered; dynamic or private; well-known
C) private or dynamic; well-known; registered
D) private or dynamic; registered; well-known
13. UDP and TCP are two protocols at the __________ layer.
A) data link
B) network
C) transport
D) application
14. Which of the following functions are performed by UDP?
A) process-to-process communication
B) host-to-host communication
C) node-to-node communication
D) None of the choices are correct
15. A port number is ______ bits long. A) 8
B) 16
C) 32
D) 64
16. Which of the following does UDP provide?
A) flow control
B) connection-oriented delivery
C) error control
D) None of the choices are correct
17. The source port number on the UDP user datagram header defines _____
8. A) B) C) 1; 1
1; 2
m -1 m -1; 1
D) 2m -1; 2m
-1
A) the sending computer
B) the receiving computer
C) the process running on the sending computer
D) None of the choices are correct
18. To use the services of UDP, we need _______ socket addresses.
A) four
B) two
C) three
D) None of the choices are correct
19. UDP packets are called _________ .
A) user datagrams
B) segments
C) frames
D) None of the choices are correct
20. UDP packets have a fixed-size header of ______ bytes.
A) 16
B) 8
C) 40
D) 32
21. TCP is a _________ protocol.
A) byte-oriented
B) message-oriented
C) block-oriented
D) None of the choices are correct
22. TCP groups a number of bytes together into a packet called a __________ .
A) user datagram
B) segment
C) datagram
D) None of the choices are correct
23. TCP is a(n) _________ protocol.
A) connection-oriented
B) connectionless
C) both connection-oriented and connectionless
D) None of the choices are correct
24. TCP is a(n) _____ transport protocol.
A) unreliable
B) best-effort delivery
C) reliable
D) None of the choices are correct
25. TCP uses ________________ to check the safe and sound arrival of data.
A) an acknowledgment mechanism
B) out-of-band signaling
C) the services of another protocol
D) None of the choices are correct
26. The bytes of data being transferred in each connection are numbered by TCP. The numbering
starts with a ________________ .
A) 0
B) 1
C) randomly generated number
D) None of the choices are correct
27. In TCP, the sequence number for each segment is the number of the ______ byte (virtual
byte) carried in that segment.
A) first
B) last
C) middle
D) None of the choices are correct
28. Communication in TCP is __________ .
A) simplex
B) half-duplex
C) full-duplex
D) None of the choices are correct
29. In TCP, the value of the acknowledgment field in a sent segment defines the sequence number
related to the ___________ byte a party expects to receive next.
A) first
B) last
C) next
D) None of the choices are correct
30. The inclusion of the checksum in the TCP segment is ______ .
A) optional
B) mandatory
C) depends on the type of data
D) None of the choices are correct
31. In TCP, a SYN segment consumes ____ sequence number(s).
A) no
B) one
C) two
D) None of the choices are correct
32. In TCP, a SYN + ACK segment consumes ____ sequence numbers.
A) no
B) three
C) two
D) one
33. In TCP, an ACK segment, if carrying no data, consumes _____ sequence number(s).
A) no
B) one
C) two
D) None of the choices are correct
34. The connection establishment procedure in TCP is susceptible to a serious security problem
called the ________ attack.
A) ACK flooding
B) FIN flooding
C) SYN flooding
D) None of the choices are correct
35. The SYN flooding attack belongs to a group of security attacks known as a ____ attack.
A) denial of service
B) replay
C) man-in-the middle
D) None of the choices are correct
36. In TCP, a FIN segment consumes ___ sequence numbers if it does not carry data.
A) two
B) three
C) no
D) one
37. In TCP, a FIN + ACK segment consumes ____ sequence number(s) if it does not carry data.
A) two
B) three
C) one
D) no
38. In TCP, one end can stop sending data while still receiving data. This is called a __________
termination.
A) half-close
B) half-open
C) full-close
D) None of the choices are correct
39. TCP sliding windows are __________ oriented.
A) packet
B) segment
C) byte
D) None of the choices are correct
40. In TCP, the size of the send window is the ______ of rwnd and cwnd.
A) maximum
B) sum of
C) minimum
D) None of the choices are correct
41. In TCP, the window should not be ________ .
A) opened
B) closed
C) shrunk
D) slide
42. In TCP, the receiver can temporarily shut down the window; the sender, however, can always
send a segment of ____ byte(s) after the window is shut down.
A) ten
B) zero
C) one
D) None of the choices are correct
43. A serious problem can arise in the sliding window operation when either the sending application
program creates data slowly or the receiving application program consumes data slowly, or both.
This problem is called the ________________ .
A) silly window syndrome
B) unexpected syndrome
C) window bug
D) None of the choices are correct
44. Nagle's algorithm can solve the silly window syndrome created by the ________ .
A) sender
B) receiver
C) both sender and receiver
D) None of the choices are correct
45. Clark's solution can solve the silly window syndrome created by the _______ .
A) sender
B) receiver
C) both sender and receiver
D) None of the choices are correct
46. Delayed acknowledgment can solve the silly window syndrome created by the _______ .
A) sender
B) receiver
C) both sender and receiver
D) None of the choices are correct
47. In TCP, an ACK segments that carry no data consumes _____ sequence number(s).
A) no
B) one
C) two
D) None of the choices are correct
48. In modern implementations of TCP, a retransmission occurs if the retransmission timer expires
or _____________ duplicate ACK segments have arrived.
A) one
B) two
C) three
D) None of the choices are correct
49. In TCP, ______ retransmission timer is set for an ACK segment.
A) one
B) a previous
C) no
D) None of the choices are correct
50. In TCP, there can be _____ RTT measurement(s) in progress at any time.
A) two
B) only one
C) several
D) None of the choices are correct
51. We need to multiply the header length field by _____ to find the total number of bytes in
the TCP header.
A) 2
B) 4
C) 6
D) None of the choices are correct
52. In TCP, urgent data requires the urgent pointer field as well as the URG bit (to be set) in the
field.
A) control
B) offset
C) sequence number
D) None of the choices are correct
53. In TCP, if the ACK value is 200, then byte ______ has been received successfully.
A) 199
B) 200
C) 201
D) None of the choices are correct
54. In TCP, the _____ timer prevents a long idle connection between two TCPs.
A) retransmission
B) persistence
C) keepalive
D) None of the choices are correct
55. In TCP, the _____ timer is needed to handle the zero window-size advertisement.
A) retransmission
B) persistence
C) keepalive
D) None of the choices are correct
56. In TCP, Karn's algorithm is used in calculations by the ______ timer.
A) retransmission
B) persistence
C) keepalive
D) None of the choices are correct
57. In TCP, a special segment called a probe is sent by a sending TCP when the ______ timer
goes off.
A) transmission
B) persistence
C) keepalive
D) None of the choices are correct
58. ________ control refers to the mechanisms and techniques to keep the load below the
capacity.
A) flow
B) error
C) congestion
D) None of the choices are correct
59. In TCP's ______ algorithm the size of the congestion window increases exponentially until
it reaches a threshold.
A) congestion avoidance
B) congestion detection
C) slow start
D) None of the choices are correct
60. In TCP's _________ algorithm the size of the congestion window increases additively until
congestion is detected.
A) congestion avoidance
B) congestion detection
C) slow start
D) None of the choices are correct
61. ______ treats the two signs of congestion detections, timeout and three duplicate ACKs, in
the same way.
A) Taho TCP
B) Reno TCP
C) new Reno TCP
D) None of the choices are correct
62. In _____ TCP, when the connection is established, TCP starts the slow start algorithms and
sets the ssthresh variable to a pre-agreed value (normally 64 or 128 kilobytes) and the cwnd variable to 1 MSS.
A) Taho TCP
B) Reno TCP
C) new Reno TCP
D) None of the choices are correct
63. The _________ added a new state to the congestion control FSM, called the fast recovery
state.
A) Taho TCP
B) Reno TCP
C) new Reno TCP
D) None of the choices are correct
64. The _________ treated the two signals of congestion, timeout and arrival of three duplicate
ACKs, differently.
A) Taho TCP
B) Reno TCP
C) new Reno TCP
D) None of the choices are correct
65. The _________ state in Reno TCP is a state somehow between the slow start and the
congestion avoidance states.
A) congestion avoidance
B) congestion detection
C) slow recovery
D) None of the choices are correct
66. In the Reno TCP, when TCP enters the fast recovery, if duplicate ACKs continue to come, TCP .
A) stays in this state, but the cwnd grows additively
B) stays in this state, but the cwnd grows exponentially
C) moves to slow start state
D) moves to the congestion avoidance state but deflate the size of the cwnd to ssthresh value
67. In the Reno TCP, when TCP enters the fast recovery, if a timeout occurs, TCP
A) stays in this state, but the cwnd grows additively
B) stays in this state, but the cwnd grows exponentially
C) moves to slow start state
D) moves to the congestion avoidance state but deflate the size of the cwnd to ssthresh value
68. In the Reno TCP, when TCP enters the fast recovery, if a new (non duplicate) ACK arrives
TCP ___________________________________ .
A) stays in this state, but the cwnd grows additively
B) stays in this state, but the cwnd grows exponentially
C) moves to slow start state
D) moves to the congestion avoidance state but deflate the size of the cwnd to ssthresh value
69. A later version of TCP, called ____ TCP, made an extra optimization on the ______ TCP.
A) New Reno; Reno
B) New Taho; Taho
C) New Reno; Taho
D) New Taho; Reno
70. In the slow start algorithm, the size of the congestion window grows _____________ until
A) exponentially; it reaches a threshold
B) exponentially; congestion is detected
C) additively; it reaches a threshold
D) additively; congestion is detected
71. In the congestion avoidance algorithm, the size of the congestion window grows congestion
is detected.
A) exponentially; it reaches a threshold
B) exponentially; congestion is detected
C) additively; it reaches a threshold
D) additively; congestion is detected
72. The congestion window size, after it passes the initial slow start state, follows a saw tooth
pattern called ________________________________ .
A) exponential increase, additive decrease
B) additive increase, exponential decrease
C) multiplicative increase, additive decrease
D) additive increase, multiplicative decrease。