CCNA2 - Examen 10习题答案

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CCNA2 -
Examen 10

1.-Which of the following
describe types of port numbers that can be represented in the header of TCP and
UDP segments? (Choose two.)
connectionless
well-known
operational
dynamic
static

2.- Which of the following
determines the amount of data that can be sent without an acknowledgment when
sending a TCP segment?
segment
number
priority
number
window
size
value in the length
field
value in the port
field
acknowledgment
number

3.-Which authority has control
over the assignment of port numbers for applications?
IEEE
IANA
InterNIC
Software Developers
Association

4.-Which of the following are
functions of the TCP protocol? (Choose three.)
translation of
data
synchronization
path
determination
flow
control
data
representation
reliability

5.-What does TCP use to ensure
reliable delivery of data segments?
upper layer
protocols
lower layer
protocols
sequence
numbers
port
numbers

6.- How are originating source
port numbers assigned during the data encapsulation
process?
assigned manually by
the user when starting the application
assigned dynamically by
the source host
assigned by the
routing protocol during the lookup process
assigned by the
destination host during session negotiation




7.-Which address is
dynamically assigned by the source host when forwarding
data?
destination IP
address
destination port
number
default gateway
address
source IP
address
source port
number

8.-What is used by both TCP
and UDP when creating a segment?
IP address
MAC address
IPX address
socket or port
number
acknowledgment
number
sequence
number

9.-What is the purpose of
Positive Acknowledgment and Retransmission (PAR)?
PAR allows the presentation layer to request
that data be resent in a format the destination host can
process.
PAR provides a mechanism for the receiving
device to request that all segments be retransmitted if one segment is
corrupt.
PAR helps ensure that a number of data segments sent by one
host are received by another host before additional data segments are
sent.
PAR is used to renegotiate the window size
during the synchronization process.

10.-A computer programmer is
developing software that requires a reliable stream of data. Which protocol can
be used in the software design to eliminate the need for building error
detection and recovery into the application program?
TCP
IP
ICMP
UDP
HTTP

11.-Which of the following
describes how TCP adds reliability to communication? (Choose
two.)
Hosts using TCP set up virtual circuits at the beginning of
the transmission using the three-way handshake.
Hosts using TCP set the error-checking
frequency at the beginning of the transmission and maintain this frequency for
the duration.
The receiving host acknowledges that it has received the
expected number of segments and requests additional
data.
The receiving host acknowledges any
incorrectly received data and requests retransmission of damaged or missing
bytes.

12.-Which of the following
protocols uses UDP for transport layer services?
SMTP
HTTP
DNS
FTP

13.-At which point in the
transmission process are segments numbered?
when
received
when
reassembling
before
transmission
while negotiating
window size

14.-During the encapsulation
process, in which order are the IP address, MAC address, and port number
assigned when the router is establishing communication with the TFTP
server?
IP address, MAC address, port
number
MAC address, IP address, port
number
port number, IP
address, MAC address
port number, MAC
address, IP address

15.-Why is TCP considered a
connection-oriented protocol?
It establishes a virtual connection between
hosts using a two-way handshake.
It uses IP to guarantee delivery of packets
between hosts.
It requires hosts to go through a synchronization process
prior to data transmission.
It creates a connection that depends on
application layer protocols for error detection.

16.-Which statement is true
regarding the TCP protocol?
Flow control at the transport layer is
provided by adding a sequence number to each segment.
A sliding window allows for communicating devices to
negotiate the amount of unacknowledged data that can be
sent.
A window size of 1 would require a receiving
device to send ACK 1 after the Segment 1 has been
received.
TCP is used by sending hosts to segment large
data files prior to transmission while IP is used by receiving host to
reassemble the smaller segments.

17.-Which of the following
describes a type of denial of service attack designed to exploit the normal
function of the TCP three-way handshake?
A host sends a packet with a spoofed source IP
address.
A host sends a packet with an incorrect
destination IP address.
A source sends a packet containing a garbled
header.
A host sends an oversized packet that fills
the memory buffers of the destination host.
A host sends a packet that contains a
virus.
A host sends a packet that contains a
worm.

18.-What type of segment and
data is shown in the graphic?
a UDP segment
carrying e-mail traffic
a TCP segment
carrying FTP traffic
an IP segment
carrying FTP traffic
a UDP segment
carrying web traffic
a TCP segment carrying web
traffic
an IP segment
carrying e-mail traffic

19.-Which transport layer unit
of information places the port number in the header?
data
segment
packet
frame
bit

20.-When a host receives a
data segment, what allows the host to determine which application should receive
the segment?
IP source address
IP destination address
PAR
sliding
window
port
number
SYN packet

21..-What is the purpose of the three-way handshake that occurs
between hosts using TCP as the transport layer
protocol?
to determine the
number of packets that can be sent before an acknowledgment is
required
to allow a host to
forward data to a router
to establish a round
trip connection between sender and receiver before data is
transferred
to provide a
mechanism for data encryption and compression

22.-What is the purpose of
using port numbers in the transport layer?
to identify the
segment as being either TCP or UDP
to provide
reliability during data transport
to identify the
interface port number used by the router when forwarding
data
to track multiple
conversations that occur between hosts

23.-Which of the following
would an administrator do to defend against a denial of service SYN flooding
attack? (Choose two.)
Hide the source of incoming IP
addresses.
Decrease the connection timeout
period.
Synchronize all host
communication.
Increase the connection queue
size.
Flood the network with false SYN
requests

24.-What is used by UDP to
determine if the data or header has been transferred without
corruption?
lower layer
protocols
checksum
PAR
sliding
window
acknowledgment and
retransmission
IP
               
               
               

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