CPSC 353 - Chapter 3
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).
