Connecting the World - Networking Essentials

2) Digital Addresses: IPv4, IPv6, Subnets, & Default Gateway

Every device on a network needs a unique address to be identified, much like every house on a street needs a street address.

• IPv4 and IPv6 Addresses

  An IP (Internet Protocol) address is the unique logical identifier for a device on a network.

  • IPv4: The legacy address format, written as four numbers separated by periods (e.g., 192.168.1.101). It uses a 32-bit structure, which allows for roughly 4.3 billion unique addresses. We have largely exhausted this address space due to the explosion of internet-connected devices.
  • IPv6: The modern address format, written as eight groups of hexadecimal numbers separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334). It uses a 128-bit structure, providing a virtually inexhaustible number of addresses.

• Subnets

  A subnet (or subnetwork) is a logical subdivision of a larger network. We use subnetting to break a large network into smaller, more manageable segments. This improves organization, enhances security by isolating groups of devices, and reduces network congestion. A subnet mask (e.g., 255.255.255.0) is used to tell a device which part of the IP address represents the network and which part represents the specific device.

• Default Gateway

  The default gateway is the IP address of the router on a local network. When a device wants to send information to a device on a different network (like a website on the internet), it doesn't know how to get there on its own. So, it sends the traffic to the default gateway. The gateway (router) then takes over and forwards the traffic toward its destination. It is essentially the "exit door" from the local network (LAN) to the outside world (WAN).