Netgear RT311 User Manual download pdf (Page 132)

Reference Guide for the Model FR314 Cable/DSL Firewall Router

B-6 Network and Routing Basics

The following table lists the additional subnet mask bits in dotted-decimal notation. To use the

table, write down the original class netmask and replace the 0 value octets with the dotted-decimal

value of the additional subnet bits. For example, to partition your Class C network with subnet

mask 255.255.255.0 into 16 subnets (4 bits), the new subnet mask becomes 255.255.255.240.

The following table displays several common netmask values in both the dotted-decimal and the

masklength formats.

Note:

The number 192.68.135.127 is not assigned because it is the broadcast address

of the first subnet. The number 192.68.135.128 is not assigned because it is the network

address of the second subnet.

Table B-1. Netmask Notation Translation Table for One Octet

Number of Bits Dotted-Decimal Value

1 128

2 192

3 224

4 240

5 248

6 252

7 254

8 255

Table B-2. Netmask Formats

Dotted-Decimal Masklength

255.0.0.0 /8

255.255.0.0 /16

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

1 2 ... 127 128 129 130 131 132 133 134 135 136 137 ... 145 146

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Netgear RT311 User Manual Page 132