The mask tells the computer which part of the address is the Street Name (Network) and which part is the House Number means "This bit belongs to the network." means "This bit is for the devices." The Classes (The Old Way) 126.255.255.254 (Huge networks) 191.255.255.254 (Medium networks) 223.255.255.254 (Small networks) Phase 2: Binary Mastery (The Apprentice) To master subnetting, you must memorize the Magic Eight . These are the values of bits in an octet: 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 If a mask is 255.255.255.128 , that last octet has the first bit turned "on." in binary = in decimal. CIDR Notation Instead of writing 255.255.255.0 Slash Notation means the first 24 bits are "on" (255.255.255.0). means the first 25 bits are "on" (255.255.255.128). Phase 3: The Subnetting Formula (The Architect)
Today, we use CIDR (Classless Inter-Domain Routing). This is the "slash notation" you see at the end of an IP, like /24. The number tells you exactly how many bits are locked for the network, giving you total flexibility to carve up IP space regardless of the old class system. The Guru Method: Subnetting in Four Steps ip subnetting from zero to guru pdf
At its simplest, subnetting is the process of taking a single large network and breaking it into smaller, manageable sub-networks. Think of it like an apartment building. The street address gets the mail to the building (the network), but the apartment numbers ensure the mail reaches the specific tenant (the host). The mask tells the computer which part of
