ZyXEL NWA1100 User Guide - Page 186

Subnetting, Table 57, Subnet Mask, Alternative, Notation, Last Octet, Binary, Decimal

Page 186 highlights

Appendix D IP Addresses and Subnetting The following table shows some possible subnet masks using both notations. Table 57 Alternative Subnet Mask Notation SUBNET MASK ALTERNATIVE NOTATION LAST OCTET (BINARY) 255.255.255.0 /24 0000 0000 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 LAST OCTET (DECIMAL) 0 128 192 224 240 248 252 Subnetting You can use subnetting to divide one network into multiple sub-networks. In the following example a network administrator creates two sub-networks to isolate a group of servers from the rest of the company network for security reasons. In this example, the company network address is 192.168.1.0. The first three octets of the address (192.168.1) are the network number, and the remaining octet is the host ID, allowing a maximum of 28 - 2 or 254 possible hosts. The following figure shows the company network before subnetting. Figure 97 Subnetting Example: Before Subnetting You can "borrow" one of the host ID bits to divide the network 192.168.1.0 into two separate subnetworks. The subnet mask is now 25 bits (255.255.255.128 or /25). The "borrowed" host ID bit can have a value of either 0 or 1, allowing two subnets; 192.168.1.0 /25 and 192.168.1.128 /25. 186 NWA1100-N User's Guide

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Appendix D IP Addresses and Subnetting
NWA1100-N User’s Guide
186
The following table shows some possible subnet masks using both notations.
Subnetting
You can use subnetting to divide one network into multiple sub-networks. In the following example
a network administrator creates two sub-networks to isolate a group of servers from the rest of the
company network for security reasons.
In this example, the company network address is 192.168.1.0. The first three octets of the address
(192.168.1) are the network number, and the remaining octet is the host ID, allowing a maximum
of 2
8
– 2 or 254 possible hosts.
The following figure shows the company network before subnetting.
Figure 97
Subnetting Example: Before Subnetting
You can “borrow” one of the host ID bits to divide the network 192.168.1.0 into two separate sub-
networks. The subnet mask is now 25 bits (255.255.255.128 or /25).
The “borrowed” host ID bit can have a value of either 0 or 1, allowing two subnets; 192.168.1.0 /25
and 192.168.1.128 /25.
Table 57
Alternative Subnet Mask Notation
SUBNET MASK
ALTERNATIVE
NOTATION
LAST OCTET
(BINARY)
LAST OCTET
(DECIMAL)
255.255.255.0
/24
0000 0000
0
255.255.255.128
/25
1000 0000
128
255.255.255.192
/26
1100 0000
192
255.255.255.224
/27
1110 0000
224
255.255.255.240
/28
1111 0000
240
255.255.255.248
/29
1111 1000
248
255.255.255.252
/30
1111 1100
252