Class B

hassantalal785

In Todd Lamlle's book it is written "Using a /16 means you are not subnetting with Class B, but it is a mask you can use." i can't understand this as /16 is default subnet of Class B .

NetworkVeteran

From Wikipedia--

Wikipedia wrote:

A subnetwork, or subnet, is a logically visible subdivision of an IP network. The practice of dividing a network into two or more networks is called subnetting.

If you're given the class B network 155.44.0.0/16, and you assign it to an interface directly--

interface Ethernet0
ip address 155.44.0.1 255.255.0.0
no shutdown

The mask is--nnnnnnnn.nnnnnnnn.hhhhhhhh.hhhhhhhh. It has 16 network bits, 0 subnet bits, and 16 host bits. You have not performed subnetting. You haven't divided the network into subnets.

If you instead do like so--

interface Ethernet0
ip address 155.44.200.1 255.255.255.0
no shutdown

The mask looks like so--nnnnnnnn.nnnnnnnn.ssssssss.hhhhhhhh. It has 16 network bits, 8 subnet bits, and 8 host bits. You have now performed subnetting, by dividing the network into subnets.