What is the difference between Class A, B and C IP hosting

The class tells you which part of the address changes as you move from one of your sites to the next. An IPv4 address has four numbers. Class C diversity varies the third, Class B the second, Class A the first. The further left the variation sits, the further apart two addresses are in the routing sense, and the harder it is to describe your estate as one block of network.

Reading the address left to right

Take an address written as a.b.c.d. The leftmost number is the coarsest division of the address space and the rightmost is an individual host. So:

• Class C varies c. Two sites live in visibly separate blocks, though those blocks may still belong to one parent network.
• Class B varies b. The sites now sit under different parent networks rather than different blocks of one.
• Class A varies a. This is the widest separation that exists to sell, because there is nothing further left to change.

Strictly speaking, classful addressing was retired from routing decades ago and modern allocation is done with prefix lengths instead. The vocabulary survived because it is a compact way of saying how far apart two addresses are, and everyone in this corner of the industry understands it.

Why supply differs so sharply

The number of blocks available at each level falls off a cliff as you move left. There are millions of possible third-octet blocks. There are far fewer second-octet parents. At the first octet the entire internet contains only a couple of hundred, and most were handed out to institutions in the earliest days of the network and have never come back. Scarcity, not any technical feature, is why the tiers are priced apart.

This shows up in order sizes as much as in cost. A Class C order can reach hundreds of addresses. Class B is measured in tens. Class A is measured in a handful, and that is not a policy choice, it is what exists.

What extra separation actually buys

Be clear about the mechanism, because it is easy to oversell. None of these tiers is a ranking signal. What varies is how much of a pattern an outside observer can reconstruct. Sites scattered across third-octet blocks look unrelated to a casual check. Sites scattered across first-octet ranges look unrelated to a determined one.

For most estates the honest answer is that Class C is sufficient and the money is better spent on content. The higher tiers earn their cost in a specific situation: a small number of properties that must not resemble anything else you own, where the cost of being grouped is high. Mixing tiers is normal and usually smarter than buying one grade for everything.

Choosing between them

Work from the risk rather than the budget. If the worry is ordinary shared-hosting neighbours, Class C solves it. If the worry is a knowledgeable person mapping your estate deliberately, the calculus changes and the wider tiers start to matter.

The sizing question is worked through in IP Classes Explained, and the practical allocation detail lives in IP Diversity. Current rates for each tier are on the product pages: Class C, Class B and Class A.