【数据通信基础】bit电信数据通信基础quiz

In _______ transmission, the channel capacity is shared by both communicating devices at all times.
full-duplex 全双工

Which organization has authority over interstate and international commerce in the communications field?
FCC

________ is a collection of many separate networks.
An internet

The _______ network was the first network.
ARPANET

Communication between a computer and a keyboard involves ______________ transmission.
simplex 单工

_______ refers to two characteristics: when data should be sent and how fast it can be sent.
Timing

______ refers to the structure or format of the data, meaning the order in which they are presented
Synax 语法

The information to be communicated in a data communications system is the _______.
Message

Frequency of failure and network recovery time after a failure are measures of the _______of a network.
Reliability

_____ refers to the physical or logical arrangement of a network.
Topology

The _______ layer coordinates the functions required to transmit a bit stream over a physical medium.
physical

As the data packet moves from the upper to the lower layers, headers are _______.
Added

The seven-layer _____ model provides guidelines for the development of universally compatible networking protocols.
OSI

Layer 2 lies between the physical layer and the _______ layer.
Network

The OSI model consists of _______ layers.
seven

The TCP/IP _______ layer is equivalent to the combined session, presentation, and application layers of the OSI model.
application

The _______ layer is responsible for delivering data units from one station to the next without errors.
data link

The ______ layer is responsible for the source-to-destination delivery of a packet across multiple network links.
network

The process-to-process delivery of the entire message is the responsibility of the _______ layer.
Transport

The Internet model consists of _______ layers.
5

In a time-domain plot, the horizontal axis is a measure of ________.
time

A signal is measured at two different points. The power is P1 at the first point and P2 at the second point. The dB is 0. This means ____.
p2 equals P1

________ is a type of transmission impairment in which the signal loses strength due to the different propagation speeds of each frequency that makes up the signal.
Distortion

Before data can be transmitted, they must be transformed to ________.electromagnetic signals

For a ______ channel, the Nyquist bit rate formula defines the theoretical maximum bit rate.
noiseless

If the bandwidth of a signal is 5 kHz and the lowest frequency is 52 kHz, what is the highest frequency?
57kHZ

Frequency and period are ______.
inverse proportional of each other

________is the rate of change with respect to time. Frequency

For a ______ channel, we need to use the Shannon capacity to find the maximum bit rate.
noisy

Given two sine waves A and B, if the frequency of A is twice that of B, then the period of B is ________ that of A.
twice

题干
Unipolar, bipolar, and polar encoding are types of _______ encoding.
line

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The Nyquist theorem specifies the minimum sampling rate to be_______.、

. twice the highest frequency of a signal

Which encoding method uses alternating positive and negative values for 1s?
AMI

If the frequency spectrum of a signal has a bandwidth of 500 Hz with the highest frequency at 600 Hz, what should be the sampling rate, according to the Nyquist theorem?
1200 samples/s

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PCM is an example of _______ conversion.
analog-to-digital

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Which quantization level results in a more faithful reproduction of the signal?
32 >16>8>2 所以选择32

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In _______ encoding, the duration of the bit is divided into two halves. The voltage remains at one level during the first half and moves to the other level in the second half. The transition at the middle of the bit provides synchronization.
both Manchester and differential Manchester

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________ is normally referred to as mB/nB coding; it replaces each m-bit group with an n-bit group.
Block coding

In _______ transmission, bits are transmitted simultaneously, each across its own wire.
. Parallel 并行传输

题干
The idea of RZ and the idea of NRZ-L are combined into the ________ scheme.
. Manchester

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In a fiber-optic cable, the signal is propagated along the inner core by __________.
reflection 全反射

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A(n) _______ medium provides a physical conduit from one device to another.
guided

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Transmission media are usually categorized as ___________.
. guided or unguided

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_______ cable can carry signals of higher frequency ranges than _______ cable.
Coaxial; twisted-pair

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In an optical fiber, the inner core is _________ the cladding.
denser than

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Which of the following primarily uses guided media?
local telephone system 本地电话系统

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________ cable is used for voice and data communications.
Twisted-pair 双绞线被用于传输语音和数据通信

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________ cables are composed of a glass or plastic inner core surrounded by cladding, all encased in an outside jacket.
. Fiber-optic

The inner core of an optical fiber is _________ in composition.
glass or plastic

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Which of the following is not a guided medium?
atmosphere

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In ________ error correction, the receiver corrects errors without requesting retransmission.
forward FEC前向差错纠正

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In modulo-2 arithmetic, we use the ______ operation for both addition and subtraction.
XOR

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A simple parity-check code can detect __________ errors.
an odd-number of

题干
Which error detection method uses one’s complement arithmetic?
. Checksum

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In cyclic redundancy checking, the divisor is _______ the CRC.
. one bit more than

The _____of errors is more difficult than the ______.
correction; detection

Which error detection method consists of just one redundant bit per data unit?
Simple parity check

题干
The checksum of 0000 and 0000 is __________.
1111

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A _____ error means that two or more bits in the data unit have changed.
burst

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In cyclic redundancy checking, what is the CRC?
The remainder

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Bit stuffing means adding an extra 0 to the data section of the frame when there is a sequence of bits with the same pattern as the ______
flag

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In Stop-and-Wait ARQ, we use sequence numbers to number the frames. The sequence numbers are based on __________arithmetic.
modulo-2

HDLC is an acronym for _______.
High-level data link control 高级数据链路控制

In ________ framing, we need a delimiter (flag) to define the boundary of two frames.
. variable-size

题干
In Stop-and-Wait ARQ, the acknowledgment number always announces in ______ arithmetic the sequence number of the next frame expected.
modulo-2

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In Selective Repeat ARQ, if 5 is the number of bits for the sequence number, then the maximum size of the receive window must be _____.
16 SR-ARG window-size=2^(5-1)=16

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In a ________ protocol, the data section of a frame is a sequence of characters.
. character-oriented 面向字符

_________control in the data link layer is based on automatic repeat request, which is the retransmission of data.
Error

题干
In the Go-Back-N Protocol, if the size of the sequence number field is 8, the sequence numbers are in ________ arithmetic,
modulo-256

题干
In the _____ Protocol, the sender sends one frame, stops until it receives confirmation from the receiver, and then sends the next frame.
Stop-and-Wait

The minimum frame length for 10-Mbps Ethernet is _______bytes.
. none of the option

题干
In Ethernet addressing, if the least significant bit of the first byte is 0, the address is _________.
unicast

1000Base-T uses ________ line coding.
4D-PAM5

题干
100Base-FX uses _________ block coding and ________ line coding.
4B/5B; NRZ-I

________uses long-wave 1310-nm single mode fiber.
. 10GBase-L

题干
__________ uses two pairs of twisted-pair cable.
100Base-TX

题干
Gigabit Ethernet access methods include _______ mode.
both full-duplex and half-duplex

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100Base-TX uses _________ block coding and ________ line coding.
4B/5B; MLT-3

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Each station on an Ethernet network has a unique _______ address imprinted on its network interface card (NIC).
. 48-bit

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The purpose of the _______ is to provide flow and error control for the upper-layer protocols that actually demand these services.
LLC LLC的功能是为上层协议提供必要的流控制和差错控制

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In IEEE 802.11, the access method used in the PCF sublayer is ______.
polling PCF层使用的是polling

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In IEEE 802.11, communication between two stations in two different BSSs usually occurs via two ________.
APs 两个不同的BSS里的station站点通信是通过2个AP

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The IEEE 802.11 standard for wireless LANs defines two services: ______ and _______.
BSS;ESS

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In IEEE 802.11, when a frame is coming from an AP and going to a station, the address flag is _______.
01 AP到station，地址标志 是01

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In Bluetooth, the _____ link is used when data integrity is more important than avoiding latency.
ACL

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In Bluetooth, the _____layer is roughly equivalent to the MAC sublayer in LANs.
baseband

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In Bluetooth, the _____ link is used when avoiding latency (delay in data delivery) is more important than integrity (error-free delivery).
SCO

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In IEEE 802.11, a BSS without an AP is called an _________.
an ad hoc architecture ad hoc architecture 自组网架构

The IEEE 802.11a, uses _________.
OFDM

The access method in Bluetooth is ________.
TDD-TDMA

题干
Find the number of addresses in a block of classless addresses if one of the addresses is 12.2.2.7/24.
256

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What is the result of ANDing 255 and 15?
15

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Identify the class of the following IPv4 address: 4.5.6.7.
A

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Which address could be the beginning address of a block of 16 classless addresses?
none of the option

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In IPv6, a ______address is used if a site with several networks uses the Internet protocols but is not connected to the Internet for security reasons.
site local

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An IPv6 address can have up to __________ colons.
7 7个冒号colons，IPv6地址是128bit，16bit（2字节）分成一组

题干
Identify the class of the following IPv4 address: 191.1.2.3.
B

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An organization is granted a block of classless addresses with the starting address 199.34.76.64/28. How many addresses are granted?
16

In IPv6, the___________ address is generally used by a normal host as a unicast address.
provider-based unicast
. provider-based unicast

题干
In IPv6, _________ address defines a group of computers.
a multicast 多播

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In IPv6, options are inserted between the _________ and the ___________ data.
base header; upper-layer data

In IPv6, the _______ field in the base header and the sender IP address combine to indicate a unique path identifier for a specific flow of data.
flow label

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The IPv4 header field formerly known as the service type field is now called the _______ field.
differentiated services

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The IPv4 header size _______.
.is 20 to 60 bytes long 其中那个20字节是固定的，没跑

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In IPv4, what is the length of the data field given an HLEN value of 12 and total length value of 40,000?
39,952

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In IPv4, an HLEN value of decimal 10 means _______.
there are 40 bytes in the header

The IPv4 header size _______.
is 20 to 60 bytes long

题干
In IPv4, what is the value of the total length field in bytes if the header is 28 bytes and the data field is 400 bytes?
428 400+28=428 字节

The ________ protocol is the transmission mechanism used by the TCP/IP suite.
IP

题干
IP is _________ datagram protocol.
both an unreliable and a connectionless

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TCP allows the sending process to deliver data as a _______of bytes and allows the receiving process to obtain data as a _________ of bytes.
. stream; stream

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UDP uses ________ to handle outgoing user datagrams from multiple processes on one host.
multiplexing 复用multiplexing

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UDP and TCP are both _______ layer protocols.
transport

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In the sending computer, UDP receives a data unit from the _______ layer.
application

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In TCP, one end can stop sending data while still receiving data. This is called a ______.
half-close 半关闭

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To accomplish flow control, TCP uses a ___________ window protocol.
sliding TCP使用滑动窗口来进行流量控制

题干
Urgent data requires the urgent pointer field as well as the URG bit in the _______ field.
：control

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TCP is a ___________ protocol.
. connection-oriented TCP是面向连接的协议

题干
An ACK segment, if carrying no data, consumes ______ sequence number(s).
no

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Because the sending and the receiving processes may not write or read data at the same speed, TCP ________.
uses buffers

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The _________ is a standard for specifying any kind of information on the Internet.
URL scheme://host:port/path/?query=asdaf#anchor

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_________ is a repository of information linked together from points all over the world.
the WWW

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A _______ document is created by a Web server whenever a browser requests the document.
dynamic

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An applet is _______ document application program.
an active
applet是用java写的小游戏， 是 active文件

The HTTP request line contains a _______ method to request a document from the server.
：GET GET方法来获取文件资源

题干
HTTP uses the services of _________ on well-known port 80.
TCP

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In a ___________connection, the server leaves the connection open for more requests after sending a response.
persistent

An HTTP request message always contains _______.
a request line and a header

题干
In a ___________ connection, one TCP connection is made for each request/response.
nonpersistent

In the Ethernet, the _______field is actually added at the physical layer and is not (formally) part of the frame.
preamble 前导码

Gigabit Ethernet has a data rate of ________Mbps.
1000Mbps

__________ uses four twisted pairs. 1000Base-T

_________ uses two fiber-optic cables. 100Base-FX

1000Base-SX, 1000Base-LX, and 1000Base-CX use _________ block coding and ________ line coding.
8B/10B; NRZ

In the Ethernet frame, the _______ field contains error detection information.
CRC

What is the hexadecimal equivalent of the Ethernet address 01011010 00010001 01010101 00011000 10101010 00001111?
5A:11:55:18:AA:0F

________ uses 1550-mm single mode fiber. 10GBase-E

The IEEE 802.3 Standard defines _________ CSMA/CD as the access method for first-generation 10-Mbps Ethernet.
1-persistent

__________ uses two optical fibers and a short-wave laser source.
1000Base-SX

In Bluetooth, the L2CAP sublayer, is roughly equivalent to the LLC sublayer in LANs.
L2CAP

In IEEE 802.11, _______ is an optional access method that can be implemented in an infrastructure network (not in an ad hoc network).
PCF

IEEE 802.11g, has a data rate of _____Mbps.
22

In IEEE 802.11, the MAC layer frame has ______ fields.
none of the option

In IEEE 802.11, when a frame is going from one AP to another AP in a wireless distribution system, the address flag is _____.
11 AP是1，station是0

In IEEE 802.11, when a frame is going from one station in a BSS to another without passing through the distribution system, the address flag is _________.
00

In IEEE 802.11, a ___ is made of stationary or mobile wireless stations and an optional central base station, known as the access point (AP).
BSS

In IEEE 802.11, a station with ________ mobility is either stationary (not moving) or moving only inside a BSS.
no-transition

In IEEE 802.11, the addressing mechanism can include up to ______addresses.
four

A Bluetooth network is called a ________. piconet 皮克网

The number of addresses in a class C block is _______.256

What is the first address of a block of classless addresses if one of the addresses is 12.2.2.76/10?
12.0.0.0

What is the default mask for class C in CIDR notation?
/24

What is the first address of a block of classless addresses if one of the addresses is 12.2.2.127/28?
12.2.2.112

In IPv6, ____ address defines a group of computers with addresses that have the same prefix.
an anycast 任播地址 定义了一群计算机有相同的地址前缀

What is the default mask for class A in CIDR notation?
/8

In IPv6, _______ address defines a single computer.
a unicast

An organization is granted a block of classless addresses with the starting address 199.34.76.128/29. How many addresses are granted?
8

Identify the class of the following IPv4 address: 229.1.2.3.
D

What is the default mask for class B in CIDR notation?
/16