Introduction to Computer Networks

Introduction to Computer Networks

• Computer networks link the world, using communication devices to allow computers to share information like digital roads.
• A computer network connects computers using communication devices for data and resource exchange.

Need of a Computer Network

• People communicate with each other to work on projects together, even remotely.
• People can share hardware resources like printers, saving money and space when on the same network.
• Computer networks are vital for global communication, storing data, video calls, audio messages, and sharing software.

Uses of Computer Networks

• Computer networks offer various daily uses including file sharing.
• Users can share data and documents with others, even in different countries.

Resource Sharing

• Computer networks enable students to share one printer in a computer lab, saving resources.

Communication

• Computer networks help team members connect and complete projects on time, even if some are away.

Database Access

• Computer networks facilitate accessing the same database from multiple computers, enhancing storage capacity and data access.

Security

• Computer networks provide data security through passwords to restrict user access.

Backup

• Computer networks store data on a central server with backup utilities, preventing data loss from accidental deletion.

Advantages of Computer Networks

• Cost Reduction is achieved by sharing hardware resources like printers and scanners across the network.
• Less Data Redundancy comes from storing all data on the server, reducing multiple copies of the same data.
• Less Data Inconsistency results from reduced data redundancy.
• Data Centralisation means the server stores all the data on the network centrally for easy accessibility.
• Data Recovery is simplified with the server's regular data backup, helping to recover data lost through network failure.

Disadvantages of Computer Networks

• Security Concerns arise from data being shared on wired and wireless mediums that allow data to be stolen.
• High Maintenance Cost results from the need for specialized teams and regular maintenance.
• Complex Architecture requires specific setups and costly equipment like cables, raising costs.
• Compatibility Issues occur when hardware and software versions must match across devices in the network
• Data Loss (In Case of Network Failure) happens if the server computer fails, leading to a complete loss of data.
• Need for Skilled Personnel includes the need for trained network managers and special teams, causing a higher maintenance cost.

Network Terminologies

• Node: A device in a computer network that can send or receive data (e.g., computer, mobile, tablet, laptop).
• Link: A connection between two computers/devices (e.g., cable, Wi-Fi, fiber optic).
• Packet: A unit of data is transferred over the internet.
• Protocol: A set of rules to be followed for sending data on a network.
• Topology: The physical arrangement of computers or devices to link with each other.
• Bandwidth: The amount of data or information that can be transmitted.
• Latency: Time taken for a message to travel from one end of the network to the other.

Network Devices

• Computer network devices are hardware components that allow computers to communicate.
• Network Interface Card (NIC) refers to a hardware component installed on a computer to connect to a network.
• Ethernet networking cable is a hardware used to connect computers and share devices (e.g., printers, scanners) in a local area network.
• Modem (Modulator-Demodulator): Sends/receives data over telephone lines, cables, or fiber optics.
• Hub: transmits received information to all devices on the network.
• Switch: it connects different computers on a network to transfer data.
• Router: routes data or information over a network, connecting subnets or subnetworks.

Types of Computer Networks

• There several types of networks and they are categorized based on the geographical area they cover.
• Personal Area Network (PAN) covers a range of 10 meters and includes wireless modems, PCs, smartphones, tablets, and printers.
• Local Area Network (LAN) extends up to a few meters across a limited region, like a school or college building.
• Metropolitan Area Network (MAN) connects devices within a metropolitan city or small town, spanning an area of up to 100 km.
• Wide Area Network (WAN) connects computers from various countries and continents, like the internet.
• Wireless Network: wireless network can be created through Wi-Fi and enables devices to connect the internet using a Wi-Fi router.

Types of Network Topologies

• Topology is a arrangement of devices (nodes) and connections in a network.
• Bus Topology: All nodes connect to a single cable and messages that are put on the cable are sent to all other nodes in a network.
• Star Topology: Nodes connect to a centralized hub, switch, or computer to form a star.
• Ring Topology: Nodes connect to each other, forming a ring and data flows unidirectionally.
• Tree Topology: Tree topology connects and links nodes in a parent-child hierarchy.
• Mesh Topology: Every node connects directly to every other node, forming a mesh.

Network Architecture

• The following architectures are used to design networks.
• Peer-to-Peer (P2P) Architecture: is where all connected computer have equal abilities.
• Client-Server Architecture: a central computer manages most of the resources.

Difference Between Peer-to-Peer and Client-Server Architecture

• Peer-to-Peer: Every node acts as both client and server. Less secure. Every node participates in network management.
• Client-Server: One or more nodes act as servers, others as clients. More secure. Most work is managed by the server.

Network Protocols

• A network protocol is a group of rules to govern how computers communicate over a network.
• Transmission Control Protocol / Internet Protocol (TCP/IP): TCP/IP is a combination of TCP and IP

Transmission Control Protocol / Internet Protocol (TCP/IP)

• TCP provides communication between computers. Then it divides data into small packets for its destination, where they are assembled again.
• IP assigns numbers for every packet so that packets can be assembled correctly at the destination.
• Hypertext Transfer Protocol (HTTP): HTTP is used to transfer data (texts, images, videos, etc.) over the World Wide Web (WWW).

Other Network Protocols

• Simple Mail Transfer Protocol (SMTP) is used to send emails between computers
• Internet Message Access Protocol (IMAP) is is a communication protocol that retrieves emails
• File Transfer Protocol (FTP) is a method to transfer files between computers over a network

Accessing a File From a Shared Drive

• A user can share data with users even if they are far away through a cloud service like Google Drive.
• Google Drive offers 15 GB of free storage capacity.

Storing a File on Google Drive

1. Sign in to your Google Account, registering if necessary.
2. Click the Google apps icon.
3. Select to click the Google Drive icon.
4. Click the New button, and choose File upload or Folder upload.

Sharing a File on Google Drive

My Drive and select the file to be shared.

1. Select My Drive, and choose File upload or Folder upload
2. Type the email addresses of recipients in the Add people and groups box, adding an optional message.
3. Select the user privileges whether the other user can edit, comment, or simply view the shared file or folder.

Network Security

• Because of security breaches on the network, network security measures are necessary.
• Firewall is a security device that monitors and filters network traffic based on the organizations security policies.
• Antivirus software is necessary to install against viruses.

Safe Online Practices

• Clear browser cookies.
• Remove unknown or unwanted applications.
• Regularly update all applications and software.
• Perform secure transactions on the portals with padlock sign.
• Keep passwords safe and strong.