Supernetting Doubt

Can supernets be used for Class B and Class C only?
Contradicting my above question, if CIDR is classless then why does the supernetting section in firewall.cx keep referring to classes, more specifically, Class C addresses?.

In wikipedia it is mentioned
"One purpose of this is to free up millions of wasted IP addresses on the Internet that classful addressing consumed."
How is this achieved?

How does supernetting work at the internet level? If a ISP has a class B address does it need to use supernetting ? Or does only organizations or companies use supernetting to aggregate their multiple network addresses?

Thanks in advance

Can supernets be used for Class B and Class C only?

Good question.

Practically Yes. However, I can imagine superneting say two Class A address spaces but who will do that? a single Class A network can hold 256^3-2 = 16777214, more than 16 million hosts, multiplied by 2, will give almost 32 million computers. If there is such an organization that has 32 million computers and all of them are behind a single ISP router!!!, poor router, then it can make sense to supernet Class A !!!

Contradicting my above question, if CIDR is classless then why does the supernetting section in firewall.cx keep referring to classes, more specifically, Class C addresses?.

A supernet: is a block of contiguous subnetworks addressed as a single subnet

This thread might help: www.firewall.cx/ftopict-5755-cidr.html

Hope this helps tgboy. Welcome to fw.cx