ccna1-4测试真题.doc

1
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Why are port numbers included in the TCP header of a segment?

to indicate the correct router interface that should be used to forward a segment

to identify which switch ports should receive or forward the segment

to determine which Layer 3 protocol should be used to encapsulate the data

to enable a receiving host to forward the data to the appropriate application

to allow the receiving host to assemble the packet in the proper order
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2
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Which is an important characteristic of UDP?

acknowledgement of data delivery

minimal delays in data delivery

high reliability of data delivery

same order data delivery
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3
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After a web browser makes a request to a web server that is listening to the standard port, what will be the source port number in the TCP header of the response from the server?

13

53

80

1024

1728
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4
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Refer to the exhibit. What two pieces of information can be determined from the output that is shown? (Choose two.)

The local host is using well-known port numbers to identify the source ports.

A termination request has been sent to 192.135.250.10.

Communication with 64.100.173.42 is using HTTP Secure.

The local computer is accepting HTTP requests.

192.168.1.101:1042 is performing the three-way handshake with 128.107.229.50:80.
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5
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Which information is found in both the TCP and UDP header information?

sequencing

flow control

acknowledgments

source and destination
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6
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With TCP/IP data encapsulation, which range of port numbers identifies all well-known applications?

0 to 255

256 to 1022

0 to 1023

1024 to 2047

49153 to 65535
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7
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Which event occurs during the transport layer three-way handshake?

The two applications exchange data.

TCP initializes the sequence numbers for the sessions.

UDP establishes the maximum number of bytes to be sent.

The server acknowledges the bytes of data received from the client.
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8
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What are two features of the User Datagram Protocol (UDP)? (Choose two.)

flow control

low overhead

connectionless

connection-oriented

sequence and acknowledgements
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9
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During a TCP communication session, if the packets arrive to the destination out of order, what will happen to the original message?

The packets will not be delivered.

The packets will be retransmitted from the source.

The packets will be delivered and reassembled at the destination.

The packets will be delivered and not reassembled at the destination.
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10
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Based on the transport layer header shown in the diagram, which of the following statements describe the established session? (Choose two.)

This is a UDP header.

This contains a Telnet request.

This contains a TFTP data transfer.

The return packet from this remote host will have an Acknowledgement Number of 43693.

This is a TCP header.
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11
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What is dynamically selected by the source host when forwarding data?

destination logical address

source physical address

default gateway address

source port
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12
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Which OSI model layer is responsible for regulating the flow of information from source to destination, reliably and accurately?

application

presentation

session

transport

network
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13
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Which transport layer protocol provides low overhead and would be used for applications which do not require reliable data delivery?

TCP

IP

UDP

HTTP

DNS
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14
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Which three features allow TCP to reliably and accurately track the transmission of data from source to destination?

encapsulation

flow control

connectionless services

session establishment

numbering and sequencing

best effort delivery
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15
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Why is flow control used for TCP data transfer?

to synchronize equipment speed for sent data

to synchronize and order sequence numbers so data is sent in complete numerical order

to prevent the receiver from being overwhelmed by incoming data

to synchronize window size on the server

to simplify data transfer to multiple hosts
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16
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Refer to the exhibit. In line 7 of this Wireshark capture, what TCP operation is being performed?

session establishment

segment retransmit

data transfer

session disconnect
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17
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Refer to the exhibit. Host A is using FTP to download a large file from Server 1. During the download process, Server 1 does not receive an acknowledgment from Host A for several bytes of transferred data. What action will Server 1 take as a result?

create a Layer 1 jam signal

reach a timeout and resend the data that needs to be acknowledged

send a RESET bit to the host

change the window size in the Layer 4 header
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18
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What mechanism is used by TCP to provide flow control as segments travel from source to destination?

sequence numbers

session establishment

window size

acknowledgments
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19
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Which two options represent Layer 4 addressing? (Choose two.)

identifies the destination network

identifies source and destination hosts

identifies the communicating applications

identifies multiple conversations between the hosts

identifies the devices communicating over the local media
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