Computer Networks Flashcards
What is the significance of linking computers through communication?
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.
What types of communication media can be used in computer networks?
Communication media can include copper lines;fiber optic cables;or radio links.
How has the use of isolated computer systems changed over the years?
Isolated computer systems have become rare;as most computers are now part of interconnected networks.
Why are today’s operating systems and software dependent on network communication?
They are designed to exchange data over a network;which is essential for their functionality.
What is discussed in the first part of the unit?
The first part focuses on the use of communication media and the basics of coding for data transmission.
What does the second part of the unit cover?
It discusses network topologies and how larger networks can be formed from individual communication networks.
What must be agreed upon before data transmission and communication can occur?
A comprehensive set of rules and conventions;known as protocols;must be established.
What is a protocol stack?
A protocol stack is a structured set of networking rules or protocols that governs communication.
Why are protocols important for computer communication?
Protocols ensure that communication proceeds in an organized and efficient manner.
How did people communicate before the digital age?
People communicated using direct speech;sounds;facial expressions;gestures;and long-distance methods like smoke signals;flags;mail correspondence;telegraphy;and analog telephones.
How do computers communicate today?
Computers communicate digitally…similar to how humans now communicate over long distances using digital technology.
Despite the trend toward digital communication;what is the nature of actual signal transmission?
Signal transmission is always analog;where digital values are mapped onto physical quantities such as current/voltage;light pulses;or electromagnetic waves.
What are common transmission media used for signal transmission?
Common transmission media include copper cables;fiber optic cables;and space for radio transmission.
What is required for transmitting a digital value like “0” or “1” over a medium?
The digital value must be mapped to a physical value of the transmission medium
Why is signal coding important in data transmission?
Signal coding ensures that valid mapping intervals are maintained despite signal distortion caused by attenuation or interference;and helps detect transmission errors.
What is line code in the context of data transmission?
Line code is the pattern used to map digital values to physical quantities for transmission and vice versa for reconstruction on the receiver side.
What is channel encoding and why is it used?
Channel encoding adds redundancy to detect and correct errors in transmission;tailoring the coding to the transmission channel’s characteristics.
When is source encoding used;and what is its effect on data transmission?
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
What is modulation in the context of line encoding?
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.
What is the difference between baseband and passband transmission?
Baseband transmission uses frequencies from zero up to the signaling rate;while passband transmission shifts signals to a higher frequency range for transmission.
What is Manchester code and how does it work?
Manchester code uses phase modulation
How does a parity check help detect transmission errors?
A parity bit is appended to each block of data
How can parity blocks help correct transmission errors?
Parity blocks for columns of data allow the receiver to detect and locate specific bit errors;enabling correction by flipping the incorrect bit.
What are the three modes of communication in computer networks?
The three modes are simplex (one-way communication);half-duplex (alternating between sending and receiving);and full-duplex (simultaneous sending and receiving).
What is multiplexing and how does it work?
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.
How does frequency multiplexing differ from time multiplexing?
Frequency multiplexing uses different carrier frequencies for parallel transmission;while time multiplexing divides a single channel into time slots for multiple data streams.
Can multiplexing be combined with different operating modes like duplex or simplex?
Yes, multiplexing can be combined with simplex, half-duplex, or full-duplex modes for flexible handling of digital data streams.
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.
How is internal communication between the CPU and memory handled in a von Neumann computer?
Internal communication is handled using buses;specifically the address bus and the data bus;for communication between the CPU and main memory.
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.
What are the challenges of using a bus topology for communication?
The main challenges are managing access to the shared medium and preventing collisions when multiple participants try to communicate simultaneously.
Why is the bus topology rarely used in modern networks?
It is less efficient than switched networks;which support duplex communication and multiplexing;allowing multiple pairs to communicate simultaneously.
What is a switch in networking?
A switch is an active network component that controls and manages simultaneous communication between multiple devices by directly connecting pairs of communication partners.
How does a switch differ from a hub?
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.
What is packet switching and why is it important in modern networks?
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.
What is a star topology?
A star topology is a network configuration where computers are connected to a central switch;allowing communication through that switch.
How does a tree topology differ from a star topology?
A tree topology extends the star configuration by connecting multiple stars through a hierarchical structure of switches;forming a larger network.
What is a mesh topology;and what is its primary advantage?
A mesh topology connects devices with redundant communication routes;providing fail-safety and resilience by allowing dynamic path selection.
What is the main drawback of a mesh topology?
Mesh topologies can be expensive to implement due to the need for multiple connections between devices.
What is a Network on a Chip (NoC)?
NoC is a network that connects components on the same microchip for internal communication.
What is a Local Area Network (LAN)?
A LAN is a network that allows computers in the same physical location;such as a building or office;to communicate with each other.
What is a Wide Area Network (WAN)?
A WAN is a network that spans across larger geographical areas;like entire countries;often using mesh topologies.
How do Metropolitan Area Networks (MANs) and Global Area Networks (GANs) differ?
A MAN connects LANs within a city;while a GAN connects networks across the globe using infrastructure like submarine cables or satellites.
What is the role of multiplexing in modern switches?
Multiplexing allows multiple data streams to be transmitted concurrently by splitting the available channel capacity into time slices or using different frequencies.
What is the OSI model and who developed it?
The OSI model is a reference model developed by the International Organization for Standardization (ISO) to describe the interaction between different protocols
Is the OSI model a standard that network manufacturers must adhere to?
No;it is not a standard; it is a model that serves as an abstract representation of a network landscape.
What is the purpose of the OSI model?
The OSI model illustrates;categorizes;and describes interfaces and protocols in network technology;contributing to interoperability;portability;and communication in computer networks.
What is the function of the physical layer in the OSI model?
It deals with physical parameters for actual data transmission;such as line codes;modulation techniques;and connector and cable types.
What are twisted pair cables and why are they commonly used?
Twisted pair cables are Ethernet cables with four pairs of wires used to reduce interference and crosstalk, commonly used today with RJ45 connectors.
What is the difference between multi-mode and mono-mode optical fiber cables?
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.
What is the primary role of the Data Link Layer?
It connects physical line codes with error detection and correction and manages access to transmission channels using media access control (MAC) protocols.
What is a MAC address and how is it structured?
A MAC address is a unique hardware address assigned to network devices;typically 48 bits long;written in hexadecimal format (e.g.
What is the function of the network layer?
It handles routing and logical addressing of data packets between subnetworks often using IP addresses.
What is the difference between a level 2 and level 3 switch?
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.
What does the transport layer do?
It ensures reliable transmission of data by breaking payloads into packets;managing error correction;and requesting retransmissions for lost packets using protocols like ARQ.
What is the difference between Stop-and-Wait ARQ and Go-Back-N ARQ?
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.
What is the role of the session layer in the OSI model?
It establishes and manages communication sessions between network computers;handling tasks like synchronization;negotiation;and session termination.
What tasks are handled by the presentation layer?
It performs data conversion;encryption;and compression;ensuring compatibility between different systems on the network.
What is an example of a standardized data format used in the presentation layer?
Extensible Markup Language (XML) is commonly used for data conversion between systems.
What is the function of the application layer?
It interacts with applications through protocol interfaces like HTTP and SMTP but does not house the applications themselves.
How do instances in the OSI model layers communicate with each other?
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.
What is the significance of the OSI model in modern network communication?
It provides a framework for understanding and designing network interactions;helping ensure communication between diverse systems and technologies.
How are modern computer systems characterized in terms of communication?
Modern computer systems are in constant communication with each other through various networks rather than being isolated terminals.
What is the basis of digital communication in computer systems?
Digital communication is based on the mapping of discrete values to physical quantities;such as electrical current/voltage;electromagnetic waves;or light pulses.
What are line codes and why are they important?
Line codes are mapping schemes that represent discrete values in physical form, crucial for data transmission over various mediums.
What role does channel encoding play in data transmission?
Channel encoding adds redundancy to the data to help detect and correct transmission errors.
What are some different operating modes used in communication channels?
Operating modes include simplex;duplex;and multiplexing.
How can communication channels be configured in modern networks?
Channels can be bundled together or interconnected to create complex topologies.
What are some examples of classic network topologies?
Classic topologies include bus;tree;and star topologies.
What advancements in technology have influenced network topologies?
The introduction of switches has enabled the creation of hierarchical topologies for local area networks and mesh topologies for wide-area communication.
What is the OSI model’s purpose in relation to network communication?
The OSI model serves as an abstract simplification of reality to illustrate;categorize;and describe interfaces and protocols in diverse network forms and extensions.
How many layers are in the OSI model and what is their significance?
The OSI model consists of seven layers, each representing different aspects of network communication and interactions between protocol.
What is the current state of the term “distributed systems”?
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.
What was the primary focus of this unit on distributed systems?
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.
What architectural concept was discussed in detail in this unit?
The concept of service-oriented architectures (SOA) and their implementation through microservices was discussed in detail.
What key topics related to SOA were covered in this unit?
The basics of communication and synchronization;as well as the concept of transactions used for persistent data storage;were covered.
How does cloud computing relate to the topics discussed in this unit?
Cloud computing embodies the aspects of SOAs and microservices;providing services aimed at both companies and end users.
What is the significance of computer clusters in the context of distributed systems?
Computer clusters are a special form of distributed systems that enable parallel high-performance computing
What role does the internet play in the evolution of distributed systems?
The internet’s pervasiveness drives the expansion and evolution of the term “distributed systems;” leading to new applications and architectures.
Why are service-oriented architectures (SOA) important in distributed systems?
SOAs allow for flexible communication and service interaction;which is essential for building scalable and interoperable distributed applications.
What is the primary benefit of using microservices in system architecture?
Micro services enable a fine-grained modularity that simplifies development;testing;and maintenance by introducing clearly defined interfaces.
