[Day 3] 1. IP Addresses and Switching

What is an IP Address? It is an unique identifier for devices on a network. IP addresses are used to: 

• Send data to the correct location on a network 

• Allow devices on different networks to communicate with each other 

• Identify a device's network interface 

• Address a device's location

• Public IP Address: Accessible by anyone on the internet.

• Private IP Address: Private IP addresses are reserved ranges of IP addresses used within local networks that are not routable on the public internet. Reserved by IANA and used within private networks. Not allowed on the public internet. Common ranges:

  • Class A:
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    10.0.0.0/8

    to
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    10.255.255.255/8

  • Class B:
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    172.16.0.0/16

    to
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    172.31.255.255/16

  • Class C:
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    192.168.0.0/24

    to
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    192.168.255.255/24

  • APIPA:
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    169.254.0.0

    to
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    169.254.255.255

    (assigned to a device automatically when it cannot obtain an IP from a DHCP server)

• NAT (Network Address Translation): Translates private IPs to public IPs, enabling devices in a private network to access the internet.

• Proxy Server: Acts as an intermediary between internal devices and the internet. Fetches data on behalf of devices.

• DHCP (Dynamic Host Configuration Protocol): Automatically assigns IP addresses and other network configurations to devices on a network.

Switching

• Switching Loop: Occurs when switches are connected in a loop, causing broadcast storms. Spanning Tree Protocol (STP) is used to prevent loops.

• Broadcast Domain: A segment where devices can broadcast to all other devices. Routers separate broadcast domains.

• Collision Domain: Each port of a switch is a separate collision domain (where packet collisions can occur).

Electrical Concepts (related to networking devices)

• Earthing: Safely directs excess electrical current to the ground.
• Live (hot) Wire: Always on the right (smaller slot in a plug).
• Neutral Wire: On the left (larger slot in a plug).
• Safety: Devices with three-pin plugs have fuses to prevent damage from electrical surges.

In a plug,

• Positive = Live = Phase
• Negative = Neutral = Return
• But earth and ground are different.(Read about it)
• Difference between earth and live should be 230 +- 6V
• How earthing works?
  • We know that electricity flows from higher potential to lower potential.
  • Earthing connects conductive materials, like metal, to the ground with a low-resistance wire. If there's a fault or overload in the system, the excess electricity flows safely to the ground instead of building up in the structure.
• What if no earthing is done?
  • Without proper earthing, electrical currents may not have a safe path to flow in the event of a fault. This can lead to electrical shock and injury to people who come into contact with electrical appliances.
• The devices with a 3 plug pin always have a fuse to save the device from higher voltage breakout.
• Why are live wires on right side and neutral on the left side?
  • Live (hot) wire is on the right (smaller slot).
  • Neutral wire is on the left (larger slot).
  • This setup ensures safety and standardization in electrical systems.

MAC Address

A MAC (Media Access Control) address is a unique hardware identification number hardcoded into network devices during manufacturing. It's a 48-bit address typically represented as six groups of two hexadecimal digits, like 00:1A:2B:3C:4D:5E. Key characteristics:

• Permanently assigned to network interface hardware
• Unique globally for each network device
• Used in local network communication
• Operates at the data link layer (Layer 2) of the OSI model
• Cannot be changed (though some devices allow MAC address spoofing)

Example: A network card's MAC address helps identify and communicate with specific devices within a local network.