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IP subnetting is the process of dividing large IP networks into smaller, manageable subnetworks or subnets. IP subnetting involves partitioning the IP address space to create multiple logical networks within a single physical network. This is done by borrowing bits from the host portion of the IP address to create the subnet portion.

Four factors make up why Subnetting is Important.
Optimizing IP Address Allocation: With the rapid growth of the internet and everyone having more devices to connect to the web like iPhones & and iPads  & gaming consoles conserving IP addresses has become crucial and subnetting allows you to use IP address space more efficiently by assigning smaller blocks of addresses to individual subnets, preventing wastage.

Efficient Network Management: Smaller subnets make it easier to manage and troubleshoot network issues like your home Wi-Fi. It helps in localizing problems within specific segments of the network, reducing the scope of network-wide outages.

Reducing Broadcast Traffic: In a flat network (no subnets), broadcast messages are sent to all devices in the network and as the network grows, this broadcast traffic can become overwhelming. Subnetting breaks the network into smaller broadcast domains, reducing the number of devices that receive broadcast messages.

 Enhancing Security: Subnets create natural boundaries that can act as security perimeters like the printer as a subnet your Xbox has. By controlling the flow of traffic between subnets, you can implement security measures and restrict communication between different parts of the network.

IP Address Classes and Reservations
     IP address classes were a way of categorizing IP addresses into different ranges to accommodate varying sizes of networks. However, it’s important to note that the classful IP addressing system is now considered deprecated, and CIDR
(Classless Inter-Domain Routing) is used for IP addressing and subnetting instead. Still, it’s useful to understand the concept. Private IP addresses are non-routable addresses used within private networks and are not meant to be used on the public internet. These addresses are defined in RFC 1918 and are used to allow multiple devices within a private network to share a single public IP address devices within a private network can communicate with each other using these private IP addresses, and a router with Network Address Translation (NAT) or network address translation capability allows these devices to access the internet using a single public IP address. This helps conserve public IP addresses and ensures better security for internal networks. See the table below for IP address classes and reserved private IP addresses. Most homes use a class A IP address and the subnet mask can be and most homes use A, B, or C for the IP. 

IP Address Classes and Range


Reserved Private IP Address Space

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Subnet Mask

The subnet mask is a critical component of IP subnetting. It helps devices determine which part of an IP address belongs to the network, which part belongs to the subnet, and which part is for the host (specific device). It has ones (1) which means on in the bit positions corresponding to the network and subnet parts, and zeros (0) which means off in the bit positions corresponding to the host part and in the IP address with a subnet mask of the first 24 bits represent the network and subnet, while the remaining 8 bits represent the host part.

Classless Inter-Domain Routing Chart

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IP Block Sizes

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Ports Numbers 

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