CPSC 353 - Chapter 3

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There are ______ bits in a port number a. 8 b. 16 c. 24 d. 32

16

There are ______ bytes in a typical TCP header, if it does not have options a. 16 b. 20 c. 32 d. 40

20

There are ______ bytes in a UDP header a. 8 b. 16 c. 24 d. 32

8

ARQ stands for

Automatic Repeat Request

Nmap is often used to: a. Decipher encrypted traffic b. Measure throughput between hosts c. Measure round-trip times between hosts. d. Do port scans over a range of ports at a target host.

Do port scans over a range of ports at a target host.

A TCP socket is fully identified by an IP address and a port number. a. True b. False

False

It is possible for an application to have reliable data transfer when using UDP a. True b. False

False

Suppose host A sends host B one segment with sequence number 38 and 4 bytes of data. Then in this same segment the acknowledgement number is necessarily 42. a. True b. False

False

Suppose that host A wants to send data over TCP to host B, and host B wants to send data to host A over TCP. Two separate TCP connections - one for each direction - are needed. a. True b. False

False

Suppose that the last SampleRTT in a TCP connection is equal to 1 sec. Then Timeout for the connection will necessarily be set to a value >= 1 sec. a. True b. False

False

The MSS is the maximum size of a TCP segment including headers. a. True b. False

False

The job of delivering the data in a transport-layer segment to the correct socket is called multiplexing a. True b. False

False

The maximum amount of data that can be placed in a segment is limited by the maximum transmission unit (MTU) a. True b. False

False

GBN stands for __________

Go back n

______________ means accepting items from more than one source. ______________ means examining data that could be intended for different destinatons and delivering the data to the correct destination. a. Demultiplexing; Multiplexing b. Multiplexing; Demultiplexing c. Encapsulation; Decapsulation d. Pulling; Pushing

Multiplexing; Demultiplexing

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

NOT D

The __________ state in Reno TCP is a state somehow between the slow start and the congestion avoidance states. a. congestion recovery b. congestion detection c. slow recovery d. None of the choices are correct

None of the choices are correct

The technique of allowing a sender to send multiple packets without waiting for acknowledgements is known as ____________

Pipelining

________ 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

Pushing; pulling

The ___________ added a new state to the congestion control FSM, called the fast recovery state. a. Tahoe TCP b. Reno TCP c. new Reno TCP d. None of the choices are correct

Reno TCP

The ___________ treated the two signals of congestion, timeout and arrival of three duplicate ACKs, differently. a. Tahoe TCP b. Reno TCP c. new Reno TCP d. None of the choices are correct

Reno TCP

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

SYN flooding

Congestion control is provided by a. UDP b. TCP c. IP d. none of the above

TCP

________ treats the two signs of congestion detections, timeout and three duplicate ACKs, in the same way. a. Tahoe TCP b. Reno TCP c. New Reno TCP d. None of the choices are correct

Tahoe TCP

In TCP, the acknowledgement number that a host puts in a segment is the sequence number of the next byte the host is expecting from the sender. a. True b. False

True

The TCP segment has a field in its header for RcvWindow. a. True b. False

True

UDP provides finer application-level control over what data is sent, and when, than TCP a. True b. False

True

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

additive increase, multiplicative decrease

Pipelining requires which of the following a. transmitting many packets before receiving acknowledgements b. unique sequence numbers for each in-transit packet c. sender-side buffering of unacknowledged packets d. all of the above

all of the above

When a TCP segment arrives to a host, the socket to which the segment is directed depends on a. the destination port number b. the source port number c. the source IP address of the datagram that encapsulated the segment d. all of the above

all of the above

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

an acknowledgment mechanism

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

an ephemeral; a well-known

TCP sliding windows are __________ oriented. a. packet b. segment c. byte d. None of the choices are correct

byte

TCP is a(n) ___________ protocol. a. connection-oriented b. connectionless c. both connection-oriented and connectionless d. None of the choices are correct

connection-oriented

UDP is a ________________ transport protocol. a. connectionless, reliable b. connection-oriented, unreliable c. connectionless, unreliable d. None of the choices are correct

connectionless, unreliable

The Internet literature ofter refersto a UDP packet as a ______________

datagram

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

exponentially; it reaches a threshold

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. last byte the party has received in the last segment b. last byte in the next segment the party expects to receive c. first byte in the next segment the party expects to receive d. None of the choices are correct

first byte in the next segment the party expects to receive

A TCP connection provides __________ duplex service a. single b. half c. full d. none of these is correct

full

Communication in TCP is ___________. a. simplex b. half-duplex c. full-duplex d. None of the choices are correct

full duplex

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

half-close

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

mandatory

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

minimum

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

move to slow start state

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

moves to the congestion avoidance state but deflate the size of the cwnd to ssthresh value

In TCP, ________ retransmission timer is set for an ACK segment. a. one b. a previous c. no d. None of the choices are correct

no

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

no

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

no

UDP has which of the following characteristics: a. three-way hand shake for connection establishment b. regulated send rate c. connection state at the server d. none of the above

none of the above

In TCP, a FIN + ACK segment consumes _____ sequence number(s) if it does not carry data. a. two b. three c. one d. no

one

In TCP, a FIN segment consumes ____ sequence numbers if it does not carry data. a. two b. three c. no d. one

one

In TCP, a SYN + ACK segment consumes _____ sequence number(s). a. no b. three c. two d. one

one

In TCP, a SYN segment consumes _____ sequence number(s). a. no b. one c. two d. None of the choices are correct

one

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

one

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

persistence

At the transport layer, to define the processes of the sender and receiver, we need two identifiers called ____________. a. logical addresses b. physical addresses c. port addresses d. None of the choices are correct

port addresses

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

process-to-process communication

A transport layer protocol provides logical communication between a. hosts b. processes c. devices d. networks

processes

TCP is a(n) _______ transport protocol. a. unreliable b. best-effort delivery c. reliable d. None of the choices are correct

reliable

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

slow start

When a UDP segment arrives to a host, in order to direct the segment to the appropriate socket, the OS uses a. the destination port number b. the source port number c. the source IP address d. all of the above

the destination port number

The source port number on the UDP user datagram header defines _______. a. the sending computer b. the receiving computer c. the process running on the sending computer d. None of the choices are correct

the process running on the sending computer

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

three

To use the services of UDP, we need ________ socket addresses. Group of answer choices a. four b. two c. three d. None of the choices are correct

two

TCP applies fast retransmit to a segment when a. the segment's timer expires b. when it receives three duplicate ACKs for an earlier segment c. it estimates unusually large RTTs d. none of the above

when it receives three duplicate ACKs for an earlier segment

The stop-and-wait protocol is highly inefficient when a. when there is a short distance between source and destination and the transmission rate is large b. when there is a large distance between source and destination and the transmission rate is high c. when there is a large distance between source and destination and the transmission rate is low d. when there is a short distance between source and destination and the transmission rate is low

when there is a large distance between source and destination and the transmission rate is high

With SYN cookies, when a server receives a SYN segment, it returns a SYNACK with: a. with a randomly chosen initial sequence number; b. initial sequence number 1; c. with an initial sequence number that is a hash of the IP addresses and port numbers in the SYN segment (as well as of other things). d. none of the above.

with an initial sequence number that is a hash of the IP addresses and port numbers in the SYN segment (as well as of other things).


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