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What is a MAC Address?

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A MAC address (Media Access Control address) is a unique identifier assigned to a network interface controller (NIC) for use as a network address in communications within a network segment. MAC addresses are primarily used for network technologies that operate in the data link layer (Layer 2) of the OSI model, such as Ethernet and Wi-Fi.

Format of a MAC Address

A MAC address is typically a 48-bit number (although some newer types use 64-bit) and is usually displayed as six groups of two hexadecimal digits, separated by colons (:), hyphens (-), or no separator. For example:

mathematica
00:1A:2B:3C:4D:5E
00-1A-2B-3C-4D-5E
001A.2B3C.4D5E

Types of MAC Addresses

  1. Unicast – Identifies a single network device.

  2. Multicast – Identifies a group of devices.

  3. Broadcast – Sent to all devices on the network (FF:FF:FF:FF:FF:FF).

Structure

A standard 48-bit MAC address includes:

  • OUI (Organizationally Unique Identifier) – The first 24 bits (first 3 bytes), assigned by IEEE, identify the manufacturer.

  • NIC Specific – The last 24 bits are uniquely assigned by the manufacturer.

For example:

makefile
00:14:22:01:23:45

  • 00:14:22 is the OUI (e.g., Dell Inc.)

  • 01:23:45 is the unique identifier for the device.

Purpose of a MAC Address

  • Device Identification: Helps uniquely identify hardware on a local network.

  • Network Communication: Used by switches and routers to forward data to the correct destination.

  • Security Filtering: Network administrators can allow or block access using MAC address filtering.

  • Tracking: MAC addresses can be used to track devices within networks (e.g., Wi-Fi).

MAC Address vs IP Address

Feature MAC Address IP Address
Layer Data Link (Layer 2) Network (Layer 3)
Scope Local network Global/Internet
Permanence Permanent (burned into NIC) Can change (dynamic/static)
Format 48-bit hexadecimal 32-bit (IPv4) or 128-bit (IPv6)

Can a MAC Address Be Changed?

Yes, although it’s usually hardcoded into the device hardware, MAC spoofing is possible using software to temporarily change it. This can be useful for:

  • Privacy protection

  • Network testing

  • Bypassing MAC filters

How to Find Your MAC Address

On Windows:

  1. Open Command Prompt

  2. Type ipconfig /all

  3. Look for “Physical Address”

On macOS/Linux:

  1. Open Terminal

  2. Type ifconfig or ip link

  3. Look for “ether” or “HWaddr”

Networking

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Networking refers to the practice of connecting computers, devices, and systems to share resources, exchange data, and communicate with each other. It enables everything from internet access and file sharing to video calls and cloud computing.

Key Concepts in Networking

1. Types of Networks

  • LAN (Local Area Network) – Small, local network (e.g., home, office).

  • WAN (Wide Area Network) – Large-scale network (e.g., the internet).

  • WLAN (Wireless LAN) – Wi-Fi-based network.

  • VPN (Virtual Private Network) – Secure, encrypted connection over a public network.

2. Basic Networking Devices

  • Router – Directs traffic between networks (e.g., home network ↔ internet).

  • Switch – Connects devices within a LAN.

  • Modem – Converts ISP signals into digital data.

  • Access Point (AP) – Extends Wi-Fi coverage.

3. IP Addresses & Protocols

  • IP Address – Unique identifier for devices (e.g., 192.168.1.1).

  • TCP/IP – Rules governing internet communication.

  • DNS (Domain Name System) – Translates domain names (e.g., google.com) into IP addresses.

4. How Data Travels

  1. You request a website (e.g., youtube.com).

  2. Your device sends data via Wi-Fi/Ethernet → Router → Modem → Internet.

  3. The request reaches YouTube’s server, which sends back the webpage.

  4. Data returns to your device through the same path.

5. Network Security

  • Firewall – Blocks unauthorized access.

  • Encryption (e.g., HTTPS, VPNs) – Protects data from hackers.

  • Authentication (e.g., passwords, biometrics) – Ensures only authorized users access the network.

Why is Networking Important?

✔ Enables internet access, streaming, gaming, and cloud services.
✔ Supports businesses (email, servers, remote work).
✔ Critical for IoT (smart homes, wearables, self-driving cars).

Example: Home Network Setup

  1. Modem connects to the ISP (gets a public IP).

  2. Router distributes internet to devices (assigns private IPs).

  3. Switch (optional) adds more wired connections.

  4. Wi-Fi Access Point extends wireless coverage.

What is router

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What is a Router?

A router is a networking device that forwards data packets between computer networks, acting as a traffic manager for your internet connection. It connects multiple devices (like smartphones, laptops, and smart TVs) to the internet through a single Internet Service Provider (ISP) connection.

Key Functions of a Router

  1. Connects Devices to the Internet

    • Allows multiple devices (via Wi-Fi or Ethernet) to share one internet connection.

  2. Directs Network Traffic

    • Acts like a “post office,” routing data between your home network and the wider internet.

  3. Assigns Local IP Addresses

    • Uses DHCP (Dynamic Host Configuration Protocol) to give each device a unique private IP address (e.g., 192.168.1.2).

  4. Provides Security (Firewall & NAT)

    • Uses Network Address Translation (NAT) to hide devices behind a single public IP (from your ISP).

    • Blocks unauthorized access with built-in firewalls.

  5. Enables Wi-Fi (Wireless Router)

    • Broadcasts a wireless signal for devices to connect without cables.

Router vs. Modem

RouterModem
Distributes internet to multiple devicesConnects directly to the ISP (one device)
Assigns local IPsGets a public IP from the ISP
Manages Wi-Fi & LANConverts ISP signal to digital data
Often combined with a modem (modem-router combo)Standalone in older setups

Common Router Features

✔ Dual-band Wi-Fi (2.4GHz for range, 5GHz for speed)
✔ Parental Controls (blocking websites/schedules)
✔ Guest Network (separate Wi-Fi for visitors)
✔ Quality of Service (QoS) (prioritizes video/gaming traffic)

Example: How a Router Works

  1. You open a website (e.g., google.com) on your phone.

  2. The router sends the request to your ISP’s modem.

  3. The modem forwards it to Google’s servers using your public IP.

  4. Google’s response comes back to the router, which delivers it to your phone.

What is IP address

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What is an IP Address?

An IP address (Internet Protocol address) is a unique numerical label assigned to every device connected to a computer network that uses the Internet Protocol for communication. It serves two main purposes:

  1. Identification – Acts like a digital “home address” for your device (computer, phone, router, etc.) on the internet.

  2. Location Addressing – Helps in routing data packets to the correct destination over the internet.

Types of IP Addresses

  • IPv4 (e.g., 192.168.1.1) – The most common format, but limited in quantity.

  • IPv6 (e.g., 2001:0db8:85a3::8a2e:0370:7334) – A newer version with more available addresses.

Public vs. Private IP Addresses

  • Public IP – Assigned by your ISP (visible to websites & online services).

  • Private IP – Used within local networks (e.g., your home Wi-Fi).

Why Do Websites See Your IP?

Websites and online services use your IP to:

  • Deliver requested content (like loading a webpage).

  • Estimate your general location (for language/region settings).

  • Enhance security (blocking suspicious activity).

Note: Your IP can reveal your ISP and approximate location (city/region), but not your exact home address or identity unless combined with other data.