Computer Networks Flashcards

1
Q

What is the significance of linking computers through communication?

A

Linking computers through communication has impacted the organization of modern computer systems;with operating systems and software now typically designed for exchanging data over a network.

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2
Q

What types of communication media can be used in computer networks?

A

Communication media can include copper lines;fiber optic cables;or radio links.

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3
Q

How has the use of isolated computer systems changed over the years?

A

Isolated computer systems have become rare;as most computers are now part of interconnected networks.

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4
Q

Why are today’s operating systems and software dependent on network communication?

A

They are designed to exchange data over a network;which is essential for their functionality.

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5
Q

What is discussed in the first part of the unit?

A

The first part focuses on the use of communication media and the basics of coding for data transmission.

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6
Q

What does the second part of the unit cover?

A

It discusses network topologies and how larger networks can be formed from individual communication networks.

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7
Q

What must be agreed upon before data transmission and communication can occur?

A

A comprehensive set of rules and conventions;known as protocols;must be established.

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8
Q

What is a protocol stack?

A

A protocol stack is a structured set of networking rules or protocols that governs communication.

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9
Q

Why are protocols important for computer communication?

A

Protocols ensure that communication proceeds in an organized and efficient manner.

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10
Q

How did people communicate before the digital age?

A

People communicated using direct speech;sounds;facial expressions;gestures;and long-distance methods like smoke signals;flags;mail correspondence;telegraphy;and analog telephones.

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11
Q

How do computers communicate today?

A

Computers communicate digitally…similar to how humans now communicate over long distances using digital technology.

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12
Q

Despite the trend toward digital communication;what is the nature of actual signal transmission?

A

Signal transmission is always analog;where digital values are mapped onto physical quantities such as current/voltage;light pulses;or electromagnetic waves.

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13
Q

What are common transmission media used for signal transmission?

A

Common transmission media include copper cables;fiber optic cables;and space for radio transmission.

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14
Q

What is required for transmitting a digital value like “0” or “1” over a medium?

A

The digital value must be mapped to a physical value of the transmission medium

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15
Q

Why is signal coding important in data transmission?

A

Signal coding ensures that valid mapping intervals are maintained despite signal distortion caused by attenuation or interference;and helps detect transmission errors.

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16
Q

What is line code in the context of data transmission?

A

Line code is the pattern used to map digital values to physical quantities for transmission and vice versa for reconstruction on the receiver side.

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17
Q

What is channel encoding and why is it used?

A

Channel encoding adds redundancy to detect and correct errors in transmission;tailoring the coding to the transmission channel’s characteristics.

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18
Q

When is source encoding used;and what is its effect on data transmission?

A

Source encoding is used to compress data before transmission;especially for data streams over low-capacity channels;like digital voice or multimedia streams. It reduces the data burden but may result in “lossy” content

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19
Q

What is modulation in the context of line encoding?

A

Modulation refers to the process of mapping digital symbols to physical quantities;such as using voltage levels for representing “0” and “1” in amplitude modulation.

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20
Q

What is the difference between baseband and passband transmission?

A

Baseband transmission uses frequencies from zero up to the signaling rate;while passband transmission shifts signals to a higher frequency range for transmission.

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21
Q

What is Manchester code and how does it work?

A

Manchester code uses phase modulation

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22
Q

How does a parity check help detect transmission errors?

A

A parity bit is appended to each block of data

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23
Q

How can parity blocks help correct transmission errors?

A

Parity blocks for columns of data allow the receiver to detect and locate specific bit errors;enabling correction by flipping the incorrect bit.

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24
Q

What are the three modes of communication in computer networks?

A

The three modes are simplex (one-way communication);half-duplex (alternating between sending and receiving);and full-duplex (simultaneous sending and receiving).

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25
Q

What is multiplexing and how does it work?

A

Multiplexing allows multiple data streams to share a communication channel by dividing it into time slices (time multiplexing) or using parallel channels;frequencies;or wavelengths.

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26
Q

How does frequency multiplexing differ from time multiplexing?

A

Frequency multiplexing uses different carrier frequencies for parallel transmission;while time multiplexing divides a single channel into time slots for multiple data streams.

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27
Q

Can multiplexing be combined with different operating modes like duplex or simplex?

A

Yes, multiplexing can be combined with simplex, half-duplex, or full-duplex modes for flexible handling of digital data streams.

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28
Q

Does the von Neumann architecture explicitly include communication with other computers?No;the von Neumann architecture does not explicitly include communication with other computers; however;communication can occur through the input/output component.

A
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29
Q

How is internal communication between the CPU and memory handled in a von Neumann computer?

A

Internal communication is handled using buses;specifically the address bus and the data bus;for communication between the CPU and main memory.

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30
Q

What is a bus topology in computer networks?A bus topology is a simple network design where multiple communication partners share a single medium;with only one partner sending data at a time while others receive it.

A
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31
Q

What are the challenges of using a bus topology for communication?

A

The main challenges are managing access to the shared medium and preventing collisions when multiple participants try to communicate simultaneously.

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32
Q

Why is the bus topology rarely used in modern networks?

A

It is less efficient than switched networks;which support duplex communication and multiplexing;allowing multiple pairs to communicate simultaneously.

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33
Q

What is a switch in networking?

A

A switch is an active network component that controls and manages simultaneous communication between multiple devices by directly connecting pairs of communication partners.

34
Q

How does a switch differ from a hub?

A

A hub is a degenerate form of a switch that only allows one communication pair at a time;while a switch can handle multiple simultaneous connections.

35
Q

What is packet switching and why is it important in modern networks?

A

Packet switching divides data into small packets, each with meta-information, allowing for efficient routing of data over shared networks. It is fundamental to the functioning of the internet.

36
Q

What is a star topology?

A

A star topology is a network configuration where computers are connected to a central switch;allowing communication through that switch.

37
Q

How does a tree topology differ from a star topology?

A

A tree topology extends the star configuration by connecting multiple stars through a hierarchical structure of switches;forming a larger network.

38
Q

What is a mesh topology;and what is its primary advantage?

A

A mesh topology connects devices with redundant communication routes;providing fail-safety and resilience by allowing dynamic path selection.

39
Q

What is the main drawback of a mesh topology?

A

Mesh topologies can be expensive to implement due to the need for multiple connections between devices.

40
Q

What is a Network on a Chip (NoC)?

A

NoC is a network that connects components on the same microchip for internal communication.

41
Q

What is a Local Area Network (LAN)?

A

A LAN is a network that allows computers in the same physical location;such as a building or office;to communicate with each other.

42
Q

What is a Wide Area Network (WAN)?

A

A WAN is a network that spans across larger geographical areas;like entire countries;often using mesh topologies.

43
Q

How do Metropolitan Area Networks (MANs) and Global Area Networks (GANs) differ?

A

A MAN connects LANs within a city;while a GAN connects networks across the globe using infrastructure like submarine cables or satellites.

44
Q

What is the role of multiplexing in modern switches?

A

Multiplexing allows multiple data streams to be transmitted concurrently by splitting the available channel capacity into time slices or using different frequencies.

45
Q

What is the OSI model and who developed it?

A

The OSI model is a reference model developed by the International Organization for Standardization (ISO) to describe the interaction between different protocols

46
Q

Is the OSI model a standard that network manufacturers must adhere to?

A

No;it is not a standard; it is a model that serves as an abstract representation of a network landscape.

47
Q

What is the purpose of the OSI model?

A

The OSI model illustrates;categorizes;and describes interfaces and protocols in network technology;contributing to interoperability;portability;and communication in computer networks.

48
Q

What is the function of the physical layer in the OSI model?

A

It deals with physical parameters for actual data transmission;such as line codes;modulation techniques;and connector and cable types.

49
Q

What are twisted pair cables and why are they commonly used?

A

Twisted pair cables are Ethernet cables with four pairs of wires used to reduce interference and crosstalk, commonly used today with RJ45 connectors.

50
Q

What is the difference between multi-mode and mono-mode optical fiber cables?

A

Multi-mode fibers have thicker cores;causing signal reflections that can distort data over long distances. Mono-mode fibers are thinner;allowing straight laser transmission;reducing signal distortion over longer distances.

51
Q

What is the primary role of the Data Link Layer?

A

It connects physical line codes with error detection and correction and manages access to transmission channels using media access control (MAC) protocols.

52
Q

What is a MAC address and how is it structured?

A

A MAC address is a unique hardware address assigned to network devices;typically 48 bits long;written in hexadecimal format (e.g.

53
Q

What is the function of the network layer?

A

It handles routing and logical addressing of data packets between subnetworks often using IP addresses.

54
Q

What is the difference between a level 2 and level 3 switch?

A

A level 2 switch uses MAC addresses for switching;while a level 3 switch (router) can switch between different network domains using logical addresses like IP.

55
Q

What does the transport layer do?

A

It ensures reliable transmission of data by breaking payloads into packets;managing error correction;and requesting retransmissions for lost packets using protocols like ARQ.

56
Q

What is the difference between Stop-and-Wait ARQ and Go-Back-N ARQ?

A

Stop-and-Wait ARQ sends one packet at a time;waiting for acknowledgment. Go-Back-N ARQ sends multiple packets and retransmits starting from the first lost or corrupt packet.

57
Q

What is the role of the session layer in the OSI model?

A

It establishes and manages communication sessions between network computers;handling tasks like synchronization;negotiation;and session termination.

58
Q

What tasks are handled by the presentation layer?

A

It performs data conversion;encryption;and compression;ensuring compatibility between different systems on the network.

59
Q

What is an example of a standardized data format used in the presentation layer?

A

Extensible Markup Language (XML) is commonly used for data conversion between systems.

60
Q

What is the function of the application layer?

A

It interacts with applications through protocol interfaces like HTTP and SMTP but does not house the applications themselves.

61
Q

How do instances in the OSI model layers communicate with each other?

A

Each layer communicates with instances in the same layer via protocols and interfaces with the layers directly above and below it to offer or use communication functions.

62
Q

What is the significance of the OSI model in modern network communication?

A

It provides a framework for understanding and designing network interactions;helping ensure communication between diverse systems and technologies.

63
Q

How are modern computer systems characterized in terms of communication?

A

Modern computer systems are in constant communication with each other through various networks rather than being isolated terminals.

64
Q

What is the basis of digital communication in computer systems?

A

Digital communication is based on the mapping of discrete values to physical quantities;such as electrical current/voltage;electromagnetic waves;or light pulses.

65
Q

What are line codes and why are they important?

A

Line codes are mapping schemes that represent discrete values in physical form, crucial for data transmission over various mediums.

66
Q

What role does channel encoding play in data transmission?

A

Channel encoding adds redundancy to the data to help detect and correct transmission errors.

67
Q

What are some different operating modes used in communication channels?

A

Operating modes include simplex;duplex;and multiplexing.

68
Q

How can communication channels be configured in modern networks?

A

Channels can be bundled together or interconnected to create complex topologies.

69
Q

What are some examples of classic network topologies?

A

Classic topologies include bus;tree;and star topologies.

70
Q

What advancements in technology have influenced network topologies?

A

The introduction of switches has enabled the creation of hierarchical topologies for local area networks and mesh topologies for wide-area communication.

71
Q

What is the OSI model’s purpose in relation to network communication?

A

The OSI model serves as an abstract simplification of reality to illustrate;categorize;and describe interfaces and protocols in diverse network forms and extensions.

72
Q

How many layers are in the OSI model and what is their significance?

A

The OSI model consists of seven layers, each representing different aspects of network communication and interactions between protocol.

73
Q

What is the current state of the term “distributed systems”?

A

The term is in a constant state of change and is expanding due to the pervasiveness of the internet;evolving into a meta-subject covering various aspects of distributed applications and system architectures.

74
Q

What was the primary focus of this unit on distributed systems?

A

The unit focused on the classical aspects and structures of distributed systems based on the requirements of IT enterprise architecture and the common client-server approach.

75
Q

What architectural concept was discussed in detail in this unit?

A

The concept of service-oriented architectures (SOA) and their implementation through microservices was discussed in detail.

76
Q

What key topics related to SOA were covered in this unit?

A

The basics of communication and synchronization;as well as the concept of transactions used for persistent data storage;were covered.

77
Q

How does cloud computing relate to the topics discussed in this unit?

A

Cloud computing embodies the aspects of SOAs and microservices;providing services aimed at both companies and end users.

78
Q

What is the significance of computer clusters in the context of distributed systems?

A

Computer clusters are a special form of distributed systems that enable parallel high-performance computing

79
Q

What role does the internet play in the evolution of distributed systems?

A

The internet’s pervasiveness drives the expansion and evolution of the term “distributed systems;” leading to new applications and architectures.

80
Q

Why are service-oriented architectures (SOA) important in distributed systems?

A

SOAs allow for flexible communication and service interaction;which is essential for building scalable and interoperable distributed applications.

81
Q

What is the primary benefit of using microservices in system architecture?

A

Micro services enable a fine-grained modularity that simplifies development;testing;and maintenance by introducing clearly defined interfaces.