## Sunday, February 11, 2007

CIDR

---------------------------------------------
255.0.0.0 /8
255.128.0.0 /9
255.192.0.0 /10
255.224.0.0 /11
255.240.0.0 /12
255.248.0.0 /13
255.252.0.0 /14
255.254.0.0 /15
255.255.0.0 /16
255.255.128.0 /17
255.255.192.0 /18
255.255.224.0 /19
255.255.240.0 /20
255.255.248.0 /21
255.255.252.0 /22
255.255.254.0 /23
255.255.255.0 /24
255.255.255.128 /25
255.255.255.192 /26
255.255.255.224 /27
255.255.255.240 /28
255.255.255.248 /29
255.255.255.252 /30

Q. IP: 210.10.10.54

Q. 220.92.92.5/24
Ans:
11011100.01011100.01011100.00000101 (Binary of 220.92.92.5) AND
11111111.11111111.11111111.00000000 (Binary of 255.255.255.0)
-----------------------------------------------------------
11011100.01011100.01011100.00000000

Subnetting Class C
-----------------------
255.255.255.128 /25 1000 0000
255.255.255.192 /26 1100 0000
255.255.255.224 /27 1110 0000
255.255.255.240 /28 1111 0000
255.255.255.248 /29 1111 1000
255.255.255.252 /30 1111 1100

Ex1: (255.255.255.192/26)

Ans:
------
@How many subnets?
192 is 1100 0000, 2 bits on
i.e 2^2=4 subnets
@How many hosts per subnet?
6 bits off,
i.e (2^6-2)=62 hosts
@Valid subnets?
256-192=64
i.e subnets are 0,64,128,192