Classless IP addressing

[mattrix100]

What is meant by classless IP addresses. How does this work?

[BillyNoMates]

It's the same as VLSM (Virtual Length Subnet Mask(ing)).

In the old days (!) IP addresses were put into classes by using a fixed subnet mask or netmask which masked on an 8 bit boundary eg. 255.0.0.0 - Class A, 255.255.0.0 - Class B etc.

With VLSM or classless addressing, more efficient use of IP addressing is available by using netmasking at the bit boundary. This gives a less rigid division of network and host addresses.

It is basically, a more efficient use of IP addresses until IP version 6, which uses a 128 bit addressing scheme, comes into widespread use.


It's not an easy question to answer in a few short sentences. Depending on your Networking knowledge, my answer may mean nothing so I could go into more detail if required.