CLASS B TRICKY EXAMPLE
Wednesday, October 29, 2008
this is some what tricky .. please do clear the concepts in the above cases
191.20.56.65 / 25 ------------
as usual ...greater than 24 .. so we need to add one more bit to make it 25 .. so tick in the table two one start horizontally and vertically and rest is gone
so seeing it ... we got under subnets the value is 128 .. so the subnet mask is
255.255.255.128
now going on with next ..we got 128 under bits so the difference is 128..but now we need to have four octet subnets for every third octet one .. if this
confuses you see the below table
start with 0------------since class b -------------x.x.0.0
subnet------------firsthost-------------lasthost------------broadcast
191.20.0.0
191.20.0.128
191.20.1.0
191.20.1.128
191.20.2.0
191.20.2.128
etc etc till our ip
191.20.56.0----------191.20.56.1-------191.20.56.126---------191.20.56.127
this satisfies our ip
191.20.56.128
hence in this way this can be determined
the crucial one
bits----------128--------64---------32---------16-------8------4------2-------1
subnets--------*
128 -------------------*
192
224
240
248
252
254
255
powers of 2 --------------------------------------- subnets--------------------------------------hosts (-2)
2
4
8
16
32
64
128
256
512
1024