Introduction to Computer Networks

Questions and Answers

What distinguishes a computer network from a distributed system?

Computer networks have a layer of middleware.

Distributed systems appear as a single coherent system to users. (correct)

Distributed systems use only fiber optics for connections.

Computer networks are always larger than distributed systems.

Which statement about the nature of connection in computer networks is true?

Connections can only be made via copper wires.

Only local area networks can use non-wired connections.

A connection must utilize the same technology for all devices.

Wireless methods such as infrared and microwaves can also establish connections. (correct)

How do users interact with machines in a computer network compared to a distributed system?

Users experience the same interface regardless of machine in both systems.

Users have no visibility of the machine's hardware in a network.

Users must log onto different machines to run programs in a network. (correct)

In a distributed system, users see multiple operating systems.

What role does middleware play in a distributed system?

It provides a cohesive model for users. Signup and view all the answers

Which of the following examples best represents a distributed system?

Cloud storage that presents a unified interface to users. Signup and view all the answers

Which network type is likely to utilize a single technology for device connection?

Local Area Network (LAN) Signup and view all the answers

What can be said about the user experience in a computer network?

Users have direct visibility of the machines' hardware and systems. Signup and view all the answers

What feature is NOT typically associated with a distributed system?

Single point of control for all resources. Signup and view all the answers

What primarily differentiates a network from a distributed system?

The software, especially the operating system Signup and view all the answers

Which of the following best describes the client-server model?

A single server can manage multiple clients Signup and view all the answers

What is one of the primary benefits of setting up a computer network for businesses?

Resource sharing among users Signup and view all the answers

Which of the following is NOT typically a goal of setting up a computer network?

Storing data on isolated computers Signup and view all the answers

Which application can be classified as one of the home applications of computer networks?

Interactive entertainment Signup and view all the answers

What role does the server play in the client-server communication process?

It performs requested work and sends replies Signup and view all the answers

E-Commerce is expected to grow quickly as it provides which advantage to customers?

Convenience of shopping from home Signup and view all the answers

In what context is the client-server model applicable?

Both local and remote connections Signup and view all the answers

What is a significant use of computer networks for mobile users?

Access to remote information Signup and view all the answers

Which type of communication is enhanced by using computer networks in businesses?

Email and video conferencing Signup and view all the answers

Which of the following is NOT a goal of computer networks?

Reducing hardware costs Signup and view all the answers

What is a distinguishing feature of a 'Star Configuration' in network topology?

All terminals are connected through a central processor Signup and view all the answers

How does implementing a firewall contribute to network security?

It prevents unauthorized access to the network Signup and view all the answers

Which of the following is a correct description of a 'Mesh Configuration'?

All remote concentrators are fully interconnected Signup and view all the answers

What is the purpose of multicasting in a broadcast network?

To allow a group of machines to receive the same message Signup and view all the answers

What action is suggested to avoid unauthorized access to a network when it is not in use?

Turn off the system and remove the network cable Signup and view all the answers

Which configuration is described as using a central processor that acts as the root and connects to multiple remote concentrators?

Tree Configuration Signup and view all the answers

What type of technology does a broadcast link utilize?

A single communication channel shared by all machines Signup and view all the answers

What characterizes a simplex connection?

Supports traffic in one direction only. Signup and view all the answers

What is a common method to secure data on a network?

Implement backup tools for data storage Signup and view all the answers

Which topology has interconnections that allow for multiple pathways for data?

Mesh Configuration Signup and view all the answers

Which of the following best describes a half duplex connection?

Only allows traffic in one direction at a time. Signup and view all the answers

What is a key characteristic of a distributed network?

It utilizes multiple interconnected networks. Signup and view all the answers

Which factor is NOT included in network criteria?

Network Maintenance Complexity Signup and view all the answers

Why is network flexibility important during design?

To allow for future upgrades and expansions. Signup and view all the answers

How is network performance primarily measured?

By analyzing request and response times. Signup and view all the answers

What does network reliability mainly depend on?

The frequency of network failures. Signup and view all the answers

What role does network management software play in distributed networks?

It manages and monitors data routing. Signup and view all the answers

What defines a full duplex connection?

Permits simultaneous traffic in both directions. Signup and view all the answers

Which is a common challenge faced in maintaining network performance?

Decreased performance with increased user numbers. Signup and view all the answers

What distinguishes peer-to-peer communication from the client-server model?

It allows individuals to communicate in a group without a central server. Signup and view all the answers

Which application is considered a 'killer application' in the interactive entertainment sector?

Video on demand. Signup and view all the answers

How can electronic commerce enhance home shopping experiences?

By providing instant videos of products. Signup and view all the answers

What is one benefit of wireless parking meters for city governments?

They allow for instant verification of payment transactions. Signup and view all the answers

What technological advancement is transforming utility meter reading?

Wireless communication for reporting usage. Signup and view all the answers

Which of the following is a potential social issue that networks could introduce?

Problems with messaging in newsgroups. Signup and view all the answers

What distinguishes the interactive entertainment category from other types of communication?

Involvement of video content and game simulations. Signup and view all the answers

What factor is contributing to the growth of the mobile computer segment?

The need for constant connectivity away from home. Signup and view all the answers

Which of the following describes a feature of peer-to-peer communication?

Any user can communicate with any other user within the group. Signup and view all the answers

What is a key aspect of future predictions for video on demand?

Users will be able to access any film ever made instantly. Signup and view all the answers

What is the primary purpose of a Metropolitan Area Network (MAN)?

Provides interconnection of Local Area Networks (LANs) within a city. Signup and view all the answers

Which of the following best describes a Wide Area Network (WAN)?

It covers large geographical areas, often nations or continents. Signup and view all the answers

What is the role of switching elements in a WAN?

To forward packets to their destination by choosing outgoing lines. Signup and view all the answers

What distinguishes a store-and-forward subnet in a WAN?

It temporarily stores packets at intermediate routers until the outgoing line is free. Signup and view all the answers

What are the components of the communication subnet of a WAN?

Transmission lines and switching elements. Signup and view all the answers

How is data transferred across a WAN?

By breaking messages into packets that are sent individually. Signup and view all the answers

Which device is commonly used as a connecting element in both MAN and WAN?

Router Signup and view all the answers

What is a characteristic of transmission lines in a WAN?

They can be copper wire, optical fiber, or radio links. Signup and view all the answers

What happens to packets when they reach an intermediate router in a WAN?

They are stored until an outgoing line is available for forwarding. Signup and view all the answers

What does a Metropolitan Area Network (MAN) typically cover?

A geographic area larger than a single city. Signup and view all the answers

What characterizes multicasting in network communications?

Delivery of a message to a group of computers in one transmission. Signup and view all the answers

Which of the following best describes point-to-point networks?

Networks that consist of many connections between individual pairs of machines. Signup and view all the answers

What primary factors define a Local Area Network (LAN)?

Size, transmission technology, and topology. Signup and view all the answers

What is a common arbitration mechanism used in bus topology networks?

Random time waiting after collision detection. Signup and view all the answers

What is the operational speed range for traditional Local Area Networks?

10 Mbps to 100 Mbps. Signup and view all the answers

Which statement accurately describes ring topology in LANs?

Bits propagate around the ring independently of the packet. Signup and view all the answers

How does a metropolitan area network (MAN) typically function?

By connecting multiple LANs for resource sharing within a city. Signup and view all the answers

What is the main difference between unicasting and multicasting?

Unicasting delivers packets sequentially, multicasting delivers them simultaneously. Signup and view all the answers

Which of the following is a feature of FDDI in networking?

It uses a ring topology for data transmission. Signup and view all the answers

What common technology does Ethernet use for LANs?

Bus topology for decentralized control. Signup and view all the answers

What is the primary function of a router in the Internet?

To forward chunks of information between incoming and outgoing links Signup and view all the answers

Which protocol is responsible for specifying the packet format sent across the Internet?

IP (Internet Protocol) Signup and view all the answers

What is meant by the term 'bandwidth' in the context of communication links?

The transmission rate, measured in bits per second Signup and view all the answers

What allows multiple end systems to share communication paths on the Internet?

Packet switching technique Signup and view all the answers

How do end systems access the Internet?

Through Internet Service Providers (ISPs) Signup and view all the answers

What term is used to describe the path that a packet takes from one end system to another?

Route or path through the network Signup and view all the answers

What type of ISPs provide Internet access to end users directly?

Residential ISPs Signup and view all the answers

What is the role of upper-tier ISPs in the Internet structure?

To interconnect lower-tier ISPs through high-speed connections Signup and view all the answers

Which of the following statements is true regarding end systems?

End systems can include various devices such as PDAs and TVs. Signup and view all the answers

What is the basic concept behind packet switching?

Dividing data into packets that can share paths on demand Signup and view all the answers

What is the role of a routing algorithm in a network?

To determine the best route for each packet Signup and view all the answers

Which individual is recognized for first conceptualizing a networked library system?

Vannevar Bush Signup and view all the answers

What was the significant outcome of the 1956 Dartmouth Artificial Intelligence conference?

It provided the first serious consideration of technology's rapid advancement Signup and view all the answers

What is the primary function of the Interface Message Processor developed for ARPANET?

To manage network traffic and packet switching Signup and view all the answers

When did the ARPANET transition to using TCP/IP protocol?

1983 Signup and view all the answers

Which event triggered the formation of the ARPA agency?

The launch of Sputnik I Signup and view all the answers

What concept did Marshall McLuhan popularize regarding technology and society?

The concept of a global village interconnected by technology Signup and view all the answers

What event marked the beginning of the Internet as a global network in the 1990s?

The retirement of ARPANET Signup and view all the answers

What was the first networking protocol used on the ARPANET?

Network Control Program Signup and view all the answers

How did the NSF contribute to the popularization of the Internet?

By transferring management to independent organizations Signup and view all the answers

What defines how communication occurs between layers in a network?

Layer n Protocol Signup and view all the answers

What is the role of an interface in the context of network layers?

To define operations and services between layers Signup and view all the answers

How does layer 3 manage message sizes in network communication?

By breaking up messages into smaller units called packets Signup and view all the answers

What is meant by 'clean interfaces' between network layers?

Interfaces that simplify the replacement of layer implementations Signup and view all the answers

What does a protocol stack consist of?

A list of protocols used by a system, one per layer Signup and view all the answers

What happens to headers as a message moves upward through the network layers?

Headers for layers below n are stripped off Signup and view all the answers

What is the main function of layer 2 in the data communication process?

To add headers and trailers to packets Signup and view all the answers

Why is it necessary for network architectures to have defined specifications?

To allow implementers to correctly build programs or hardware for each layer Signup and view all the answers

What is a significant advantage of having different implementations for the same layer protocol?

It allows for flexibility in technology choices Signup and view all the answers

Which layer is responsible for determining the routes packets take within the network?

Layer 3 Signup and view all the answers

What is the primary purpose of addressing in computer networks?

To identify senders and receivers within the network Signup and view all the answers

Which design issue in networking addresses the problem of maintaining the order of messages?

Error control Signup and view all the answers

Flow control in network communication aims to achieve which of the following?

Balancing the data transmission rates between sender and receiver Signup and view all the answers

What is multiplexing in the context of computer networks?

Gathering messages into a single connection to improve efficiency Signup and view all the answers

In a connection-oriented service, what is the first action a user must take?

Establish a connection Signup and view all the answers

When a network has multiple paths available, what is the process of choosing a specific route called?

Routing Signup and view all the answers

Which of the following best describes a challenge associated with error control in networking?

Agreeing on error-detecting and error-correcting codes Signup and view all the answers

Which aspect is NOT typically a focus of flow control mechanisms in networking?

Establishing a reliable connection for high-speed transmission Signup and view all the answers

What determines the logical channels in data transfer within a network?

The requirements set by the communication protocol Signup and view all the answers

Which statement is true regarding connectionless services?

Data transmission can happen without prior connection setup Signup and view all the answers

What is the primary function of firewalls in private networks?

Restricting the flow of messages to and from the network Signup and view all the answers

Which of the following best describes the connection-oriented reliable service provided by the Internet?

It guarantees data delivery without errors. Signup and view all the answers

How many different RFCs are currently available as standards for the Internet?

More than 3,000 Signup and view all the answers

What is the role of the Internet Engineering Task Force (IETF)?

To create, test, and implement Internet standards Signup and view all the answers

What is the significance of protocol hierarchies in network design?

They offer certain services to higher layers while hiding implementation details. Signup and view all the answers

What does the term 'intranet' refer to?

A private network using Internet technology Signup and view all the answers

Which of the following statements is true about connectionless unreliable service?

It makes no promises regarding message delivery. Signup and view all the answers

Which approach was historically taken in designing computer networks?

Prioritize hardware over software in design considerations Signup and view all the answers

Which service does the Internet currently lack in terms of data delivery?

Promises regarding the delivery time of data Signup and view all the answers

What does each layer of a network's protocol hierarchy provide to the layer above it?

Specific services and functions Signup and view all the answers

What is a key characteristic of connection-oriented service?

The sender and receiver negotiate parameters for communication. Signup and view all the answers

Which of the following best describes connectionless service?

Messages are routed independently without maintaining sequence. Signup and view all the answers

What typically distinguishes reliable connection-oriented service from unreliable services?

It involves the receiver acknowledging the receipt of each message. Signup and view all the answers

Which scenario is most appropriate for using a reliable connection-oriented service?

Transferring a large file. Signup and view all the answers

What is one downside of incorporating acknowledgment in message delivery?

It can introduce overhead and delays. Signup and view all the answers

In what scenario is connectionless service generally preferred?

For applications where speed is more important than reliability. Signup and view all the answers

Which type of service is often termed as 'datagram service'?

Unreliable connectionless service without acknowledgment. Signup and view all the answers

How does a reliable connection-oriented service manage message boundaries?

It preserves message boundaries between distinct messages. Signup and view all the answers

What is a key requirement for connection-oriented services?

A physical path must be established before communication begins. Signup and view all the answers

Which application might not require a reliable service?

Email notifications. Signup and view all the answers

Study Notes

Introduction to Computer Networks

A computer network is a collection of interconnected computing hardware devices facilitating communication and resource sharing.
Interconnections can occur through various mediums: copper wires, fiber optics, microwaves, infrared, or communication satellites.
Networks are categorized by size and scope: Local Area Network (LAN), Metropolitan Area Network (MAN), and Wide Area Network (WAN).
Key difference between a computer network and a distributed system: a distributed system presents itself as a single coherent system to users, while a computer network exposes actual machines.

Uses of Computer Networks

Business Applications: Focus on resource sharing, like accessing databases remotely from client machines to servers, forming the client-server model.
Home Applications: Include accessing remote information, person-to-person communication, and e-commerce.
Mobile Users: Wireless technology enables connection for mobile devices, enhancing functionalities like wireless parking meters and smart utility meters.
Social Issues: Networking can raise ethical and social concerns, particularly around communication platforms like newsgroups and bulletin boards.

Direction of Data Flow

Simplex: One-way communication, e.g., an optical fiber where data flows in a single direction.
Half Duplex: Two-way communication, but one direction at a time, e.g., a single railroad track.
Full Duplex: Simultaneous two-way communication, e.g., a two-lane road.

Networks

Distributed Processing

A distributed network comprises various networks that can be managed jointly or separately, distributing processing and data communication.
Operates under a client/server architecture where a central server provides resources for multiple remote users.

Network Criteria

Network Performance: Important for achieving desired functionality; affected by the number of users and type of transmission medium.
Network Reliability: Measured by failure frequency, recovery time from failures, and protection from disasters.
Network Security: Essential for safeguarding against viruses and unauthorized access; measures include antivirus software and firewalls.

Goals of Computer Network

Resource Sharing: Ensures data and equipment are available regardless of location.
High Reliability: Enables replication of files on multiple machines to ensure availability.
Cost Savings: Allows centralized data storage on shared file server machines leading to economic efficiencies.
Increased System Performance: Can improve by adding processors as workloads grow.

Different Types of Network Topologies

Star Configuration: Central processor connected to multiple terminals.
Tree Configuration: Hierarchical structure with central and remote concentrators.
Ring Configuration: Connects terminals in a loop, allowing data to travel in either direction.
Mesh Configuration: Fully interconnected remote concentrators with a central processor.
Bus Configuration: Linear connection where only one machine can send data at a time.

Categories of Network Hardware

Broadcast Links: Single communication channel shared by all machines; allows messages to be sent to all or a subgroup (multicasting).
Point-to-Point Links: Direct connections between individual pairs of machines; often more common in larger networks.

Local Area Networks (LANs)

LANs are privately owned networks restricted in size, typically within a building or campus, mainly for sharing resources and information exchange.
Characterized by their transmission technology, architecture, and size, with speeds ranging from 10 Mbps to 10 Gbps in newer models.### Network Types and Topologies
Line speeds measured in megabits/sec (1 Mbps = 1,000,000 bits/sec) and gigabits/sec (1 Gbps = 1,000,000,000 bits/sec).
Bus topology allows only one machine to transmit at a time; requires an arbitration mechanism to resolve conflicts.
IEEE 802.3 (Ethernet) operates at speeds of 10 Mbps to 10 Gbps and features decentralized control, allowing computers to retransmit after collisions.
Ring topology has each bit traveling independently, with methods like token passing to manage access.
IEEE 802.5 (IBM token ring) operates at 4 and 16 Mbps.

Metropolitan Area Network (MAN)

Covers city-wide areas, connecting multiple LANs for shared resources and services.
MANs may be privately owned or provided by public companies.
Typical examples include cable television networks that evolved from community antenna systems.
Geographical coverage can range from several blocks to entire cities (up to 50 km).

Wide Area Network (WAN)

Spans large geographical areas like countries or continents, composed of hosts connected by a communication subnet.
Hosts owned by customers; subnet typically owned by phone companies or ISPs.
Subnet comprises transmission lines (copper wire, fiber optics) and switching elements (routers).
Packets transmitted between hosts follow a store-and-forward method, which involves stopping and routing at intermediate routers.
Packet-switching technology allows multiple communications to share routes non-dedicated paths.

History of the Internet

Conceptual development driven by individuals like Vannevar Bush, Norbert Wiener, and events like the 1956 Dartmouth conference.
ARPANET launched in 1969 with the first protocols established for communication.
TCP/IP protocol replaced early protocols in 1983, becoming the global standard for networking.
Growth accelerated in the 1990s, leading to the transfer of management from government to independent organizations in 1995.

Current State of the Internet

The Internet is a global network enabling communication and access to resources via different types of devices (PCs, mobile devices, appliances).
Access through Internet Service Providers (ISPs) who connect end systems using various bandwidth methods (dial-up, broadband, etc.).
Routers play a crucial role, forwarding packets across the network based on routing algorithms.
The Internet employs packet-switching to efficiently manage multiple communications over shared paths.

Internet Protocol Standards

The Internet operates using protocols like TCP and IP, which define packet formats and manage data transmission.
Standards are maintained by the Internet Engineering Task Force (IETF) via RFCs (Request for Comments), establishing protocols for data handling.
The Internet provides connection-oriented reliable service and connectionless unreliable service for application communications.
Private networks (intranets) utilize similar protocols and structures as the public Internet but are restricted in communication with external hosts.

Network Software Structure

Network software is organized hierarchically in layers, each offering different services and abstraction from implementation details.
Protocols define how communication proceeds between layers and devices, ensuring data is passed correctly through the network stack.
Clear interfaces between layers facilitate the implementation and modification of network systems without altering services provided to higher layers.
A network architecture comprises the arrangement and protocols of layers, crucial for building or programming each layer effectively.### Architecture and Protocols
Implementation details and interface specifications are not included in system architecture; they are hidden within machines.
Machines in a network can utilize different interfaces, as long as they adhere to the required protocols.
A protocol stack consists of a list of protocols used by a system, one per layer of the network architecture.
Layer 3 protocol limits message sizes, often requiring Layer 3 to divide larger messages into smaller packets with headers.
At Layer 2, each packet receives additional headers and trailers before reaching Layer 1 for physical transmission.
Received messages move upward through layers, stripping off headers without passing lower layers' headers to the higher ones.

Key Design Issues in Layers

Addressing: Each layer requires a method for identifying senders and receivers; essential in networks with many computers and processes.
Data Transfer: Protocols determine data directionality (one-way or two-way) and manage multiple logical channels for different data types.
Error Control: Essential for communication accuracy; both ends must agree on error-detection/correction methods and maintain message order.
Flow Control: Prevents fast senders from overwhelming slow receivers through feedback mechanisms or transmission rate limits.
Multiplexing and Demultiplexing: Enables the handling of long messages by breaking them into smaller parts and combining smaller messages for efficiency.
Routing: Involves selecting the best path for data across multiple options, influenced by high-level and low-level decisions.

Connection-Oriented vs Connectionless Services

Connection-Oriented Service:
- Modeled after telephone systems; requires a pre-established connection.
- Maintains the sequence of packets; messages are consistently delivered in the order sent.
- Often includes parameter negotiation regarding message size and quality of service.
Connectionless Service:
- Modeled after postal systems; each message has a complete address and operates independently.
- Does not guarantee the order of packet delivery; efficiency emphasized over reliability.
- Acknowledgements for reliable delivery increase overhead; suitable for applications like file transfer that require accuracy.
- Variants include message sequences (preserving message boundaries) and byte streams (no message boundaries).
- More appropriate for applications such as voice or video conferencing where delays are undesirable, but some data loss is acceptable.

Applications and Reliability Considerations

Reliable connection-oriented services cater to applications requiring data integrity, like file transfers, while managing message boundaries.
Connectionless services benefit users who need to send short messages without establishing a connection, trading off complete reliability.
Datagram service refers to unreliable connectionless service, likening it to telegrams which do not require sender acknowledgements.

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Description

This quiz covers the basics of computer networks, focusing on the definition and functionality of networked systems. Explore the significance of interconnecting computers and the channels that facilitate communication and resource-sharing among users.