What exactly does Class B buy me over Class C

A different parent network rather than a different block inside one. Class C changes the third number in the address; Class B changes the second. Two addresses that differ in the second octet do not merely sit in separate blocks, they sit under separate upstream allocations, which is a wider gap than most people realise when they compare the two on a price list.

The concrete difference

Imagine two sites on third-octet diversity. Their addresses differ in the third position. Anyone examining them sees two distinct blocks, which is exactly the point, but those blocks may still roll up to the same parent allocation. Someone looking one level up rather than at the address itself can still find the relationship.

Second-octet diversity removes that. The parent allocation differs too, so the relationship does not survive a look upward. The check that would have grouped the sites no longer returns both.

Where it sits in supply

Class B is the middle tier by construction. There is far more of it than first-octet space, which is effectively fixed, and far less than third-octet space, which is abundant. A Class B order is measured in tens of addresses rather than hundreds or single digits, and the European allocation is smaller than the American one, as it is at every tier.

That middle position is the whole argument for it. It is the tier you reach for when third-octet separation feels thin for a particular set of properties but the widest tier cannot supply the quantity you need or justify its rate across that many sites.

When it is the right answer

• A cluster within a larger estate. Ten or fifteen related properties you would rather were not traceable to each other, sitting inside a bigger network that runs on Class C.
• Quantity beyond what the top tier supplies. When the list of sensitive properties runs past what a Class A order can hold.
• Clients under one roof. Where separation between customer estates matters more than separation within them.

When it is not

If the estate is large and mostly ordinary, buying the middle tier for all of it is a poor trade. It costs materially more than third-octet diversity and does not move the needle on the footprints that actually give networks away: shared templates, batch-registered domains, a single analytics identifier, mechanical interlinking. Those survive every tier equally.

The pattern that works is layered. Third-octet diversity as the floor, a wider tier for the cluster that needs it, and honest attention to everything above the network layer. Buying one grade for everything is simpler to reason about and almost always the wrong shape.

Rates and order limits for the middle tier are on the Class B page for the American pool and the European one. The tier comparison is in IP Classes Explained.