chapter 6 configuring network adressing

Introduction

  • Discussion of varying levels of experience among students.
    • Acknowledgment of different backgrounds and starting points in learning.

IP Addresses

  • Definition of IP address:
    • Used by devices to find and communicate with each other in a network.
  • Types of IP addresses:
    • IPv4 (IP Version 4)
    • IPv6 (IP Version 6)
    • A+ level focus is primarily on IPv4; knowledge of IPv6 is a bonus for A+ and mandatory for N+.

Historical Context

  • Use of IPv4 until around 2007.
    • Operating systems supporting only IPv4 include:
    • Windows XP
    • Windows Server 2003
  • Introduction of IPv6:
    • Windows Vista (often pronounced differently based on the region) is the first Microsoft OS to support IPv6.
    • Windows Server 2008 also supports IPv6.

Understanding IPv4 Addressing

  • An example IPv4 address: 192.168.0.15
  • Composition of an IPv4 address:
    • Consists of 4 octets (segments) divided by periods.
    • Each octet contains 8 bits.
    • Example breakdown:
    • First octet: 192
    • Second octet: 168
    • Third octet: 0
    • Fourth octet: 15
  • Calculation of total bits in an IPv4 address:
    • Formula: 8 bits × 4 octets = 32 bits.
    • Thus, an IPv4 address consists of 32 bits (not 52 bits as mistakenly stated earlier).

Conversion Between Decimal and Binary

  • Decimal: counts from 0-9.
  • Binary: uses only 0s and 1s.
  • Conversion learning resources available for further study.

Types of IP Addresses

Public vs Private IP Addresses

  • Public IP Address:
    • Routable on the internet.
    • Different from the private IP address used within a local network.
  • Private IP Address:
    • Used within a local home or office network.
    • Configurable by the user through manual settings (static) or DHCP.
    • Not routable on the internet.
  • DHCP (Dynamic Host Configuration Protocol) facilitates dynamic assignment.

Sharing Public IP Addresses

  • Multiple devices (e.g., home/office) may share a single public IP address when accessing the internet.
  • Benefits of using shared public IP:
    • Eases configuration with cloud services.
  • Drawbacks of shared public IP:
    • Risk of blocking; actions of one device may affect others.
    • Example: social media accounts can be banned based on shared IP.

Classifying IP Addresses

IP Address Classes

  • Importance of knowing different classes for exams.
  • Class A
    • Example: Begins with 10.x.x.x.
    • Supports over 16 million addresses.
  • Class B
    • Example: Begins with 172.16.x.x.
    • Supports around 65,000 addresses.
  • Class C
    • Example: Starts typically with 192.168.x.x.
    • Supports 256 IPs (254 usable, as first and last are reserved).

Subnet Mask Notation

  • Class C example:
    • Default: 255.255.255.0 (indicates a /24 network mask).
  • A changing last octet in the subnet mask indicates further subdivision of the network.

DHCP (Dynamic Host Configuration Protocol)

Overview

  • Functionality of DHCP:
    • Automatically assigns IP addresses from a defined scope.
    • Can be integrated into home routers or dedicated DHCP servers.
  • Scope definition and configuration:
    • Range of IPs determined by technician or router configuration.
    • Example scope: 192.168.0.50 to 192.168.0.100.

Lease Mechanism

  • DHCP leases: IPs typically valid for a specific period, often 24 hours.
  • When an IP lease expires, the device may lose connectivity until renewed or released.

Reservations and Exclusions in DHCP

  • Reservations:
    • Assign a specific IP address to a device every time it connects, such as printers.
  • Exclusions:
    • Prevent certain IPs from being issued dynamically, often used for servers.

DNS (Domain Name System)

Purpose of DNS

  • Converts domain names to IP addresses (and vice versa).
  • Essential for human comprehension of internet navigation.
  • Example: Typing 'youtube.com' triggers a request for its IP address via DNS.

Functionality of DNS

  • DNS lookup process:
    • The computer queries DNS for the IP of a website,
    • Receives an 'A record' with the IP address.
  • Short-term memory:
    • Devices may cache previously visited URLs, expediting future access.
  • Clearing cache involves using the command:
    • ipconfig /flushdns to force the device to request the current IP from DNS again.

VLAN (Virtual Local Area Network)

Definition and Purpose

  • VLANs create multiple virtual networks within the same physical infrastructure.
  • Utilized for separating different types of traffic:
    • Example: VLAN for HR and another for marketing.

Configuration

  • Requires a managed switch for configuration.
  • Advantages:
    • Cost-effective; utilizes existing cabling.

VPN (Virtual Private Network)

Purpose and Usage

  • VPNs enable secure remote connections to a network (often used for office connectivity).
  • Provides an encrypted tunnel for data, ensuring privacy and security.