SUB NET MASKING And IP Address Classes

SUB NET MASKING

–Smaller broadcast domains

–More manageable networks

–Save IP Addresses

Default Subnet Mask

–CLASS A  - 255.0.0.0

–CLASS B  - 255.255.0.0

–CLASS C  - 255.255.255.0

SUB NET MASKING

4000 Hosts

NET ID – 190.100.0.0

CLASS B

212=4096

D.S.M  - 255.255.0.0

255.255.11110000.00000000

255.255.240.0 is the Sub net

256-240 = 16

IP Address Classes

•Class A

–N.H.H.H

–1-126

–0 can not be used as Net ID

–127 is reserved for loop back functions

–126 Different Networks

–16.777.214 Hosts per Network

•Class B

–N.N.H.H

–128-191

–The first IP Address is the NET ID

–The last IP Address is the Broadcast Address

–16.384 Different Networks

–65543 Hosts per Network

•Class C

–N.N.N.H

–192-223

–The first IP Address is the NET ID

–The last IP Address is the Broadcast Address

–2.097.152 Different Networks

–254 Hosts per Network

CLASS D 

– Used for multicast broadcasts

CLASS E – Experimental addresses not available to the public