Computer Network Notes

Computer Concepts Overview

  • Networks facilitate communication between computing devices.
  • Understanding computer operations is crucial for grasping networks.
  • Routers and switches are specialized computers for network data movement.

Basic Functions of a Computer

  • Input: Receiving information (e.g., keyboard).
  • Processing: CPU interprets information.
  • Output: Displaying results (e.g., monitor).

Components

  • Input: Keyboards, microphones, webcams, scanners, USB ports.
  • Processing: CPU executes instructions from programs and OS.
  • Output: Monitors, printers, storage, network cards, speakers, USB ports.

Storage Components

  • Short-term (RAM): Volatile, fast access (nanoseconds).
  • Long-term: Non-volatile, slower access (milliseconds), e.g., hard disks, CDs/DVDs, USB flash drives.

Computer Boot Procedure

  • Power to motherboard.
  • CPU starts.
  • CPU executes BIOS startup routines (POST).
  • Boot devices are searched for an OS.
  • OS is loaded into RAM.
  • OS services start.

OS and Hardware Interaction

  • OS provides user interface, memory management, file system, multitasking, and hardware interfacing.

Key services

  • User Interface: Enables user interaction via GUIs.
  • Memory Management: Allocates and deallocates memory for applications.
  • File System: Organizes storage on devices.
  • Multitasking: Allows running multiple applications simultaneously.
  • Interface to Hardware Devices: Uses device drivers for hardware communication; uses interrupts to signal the OS.

Fundamentals of Network Communication

  • Networks enable resource and information sharing.

Network Components:

  • NIC (Network Interface Card): Connects a computer to the network.
  • Network Medium: Cable or airwaves for connection.
  • Interconnecting Device: Switches, hubs, routers, wireless access points.

Network Terms

Clients and Servers

  • Client: device or software that requests network resources.
    • Client OS examples: Windows 7, Mac OS X.
  • Server: provides network services to clients.
    • Server OS examples: Windows Server 2008, Linux.

Packets and Frames

  • Data is transferred in chunks (packets or frames).
  • Packet: data with source and destination IP addresses.
  • Frame: packet with source and destination MAC addresses and error-checking code.
  • Encapsulation: Adding headers and trailers to data.

Network Types

  • LAN (Local Area Network): Small network in a limited area.
  • Internetwork: Collection of LANs connected by routers.
  • WAN (Wide Area Network): Geographically dispersed LANs connected over long distances.
  • MAN (Metropolitan Area Network): WAN technologies in a specific region (city or county).