ZyXEL VFG6005 User Guide - Page 109

Subnetting

Page 109 highlights

For example, 192.1.1.0 /25 is equivalent to saying 192.1.1.0 with subnet mask 255.255.255.128. The following table shows some possible subnet masks using both notations. Alternative Subnet Mask Notation SUBNET MASK ALTERNATIV LAST OCTET LAST OCTET E NOTATION (BINARY) (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 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. 100

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For example, 192.1.1.0 /25 is equivalent to saying 192.1.1.0 with subnet mask 255.255.255.128.
The following table shows some possible subnet masks using both notations.
Alternative Subnet Mask Notation
SUBNET
MASK
ALTERNATIV
E 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
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.