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I posted the following over on my twitter account – it’s here to make it easy to reference.

Plus I have more information that just won’t fit in 140 characters.

I’ve cleaned it up to make it more readable.

On twitter:

Class C IP address ranges stopped being given out before 1994.

So when you hear SEO guys and girls as well as marketers talking about Class C IP addresses and hosting, their talking complete and utter B.S.

Want proof see:
RFC 1338
RFC 1519
RFC 4632

Or you can take a look at Classful network over at Wikipedia

There are a number of places using real Class C IP address ranges but their not going to be your average hosting provider.

I’ve worked for an institution which had been allocated, back in the day – 65 real public Class C IP address ranges.

I used 5 of them to build a wireless network that covered 7 locations (10 physical buildings) and was actively used by 650+ users.

I also managed another 35 real Class C IP address range networks – where each range was a physical network.

So I know a real Class C IP address range from a classless /24 range – which is what is in use today.

They’ll probably next start talking about sites within the same BGP domain and then sites with in the same AS domains and then finally sites hosted on earth.

When they do, you read it here first.

I found the following description of what a Class C IP address is over at gotwebhost.com, they sell so called Class C IP address plans.

What follows is complete and utter Bull Sh*t.

What are “Multiple Class C IP Addresses?”

An IP is an Internet Protocol address which is a numeric address. This address looks like 12.34.567.890 and is in the format A.B.C.D. In the 12.34.567.890, the 567 is in the C place. When you have multiple Class C IP’s, they have different C numbers. Modern web hosting companies, if they give you multiple IP’s, give them in the same A.B.C class, but with a different D.

Heres what the calsses are:

Class Range Allocation
A range = 0.0.0.0 to 127.255.255.255
B range = 128.0.0.0 to 191.255.255.255
C range = 192.0.0.0 to 223.255.255.255
D range = 224.0.0.0 to 239.255.255.255

The way it works out as – is:

A range = N.H.H.H
B range = N.N.H.H
C range = N.N.N.H
D range = Not applicable

Key:

N = Network part of the address
H = Host part of the address

An example Class C IP address is 192.168.0.1
It’s a class C IP address because it begins with 192 which is in the 192.0.0.0 to 223.255.255.255 range.

But as I said at the beginning of this post – Class C IP address stop being given out over 10 years ago. Which makes it even more of a bigger pile of Bull Sh*t.