Class AE Addresses


Class

Leading Bit Pattern

First Octet in Decimal

Notes

A

0xxxxxxx

0127

0 is invalid

127 reserved for loopback testing

B

10xxxxxx

128191

 

C

110xxxxx

192223

 

D

1110xxxx

224239

Reserved for multicasting

E

1111xxxx

240255

Reserved for future use/testing


Formulae

2N

Where N is equal to number of bits borrowed

Number of total subnets created

2N 2

Number of valid subnets created

2H

Where H is equal to number of host bits

Number of total hosts per subnet

2H 2

Number of valid hosts per subnet


Class A Address

N

H

H

H

Class B Address

N

N

H

H

Class C Address

N

N

N

H


N = Network bits

H = Host bits

All 0s in host portion = Network or subnetwork address

All 1s in host portion = Broadcast address

Combination of 1s and 0s in host portion = Valid host address




CCNA Self-Study(c) CCNA Portable Command Guide
CCNA Portable Command Guide
ISBN: 1587201585
EAN: 2147483647
Year: 2006
Pages: 261
Authors: Scott Empson

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