Example eight subnets, Subnetting with class a and class b networks – ZyXEL Communications ZyXEL ZyWALL 35 User Manual
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ZyWALL 35 User’s Guide
602
Appendix C IP Subnetting
Example Eight Subnets
Similarly use a 27-bit mask to create 8 subnets (001, 010, 011, 100, 101, 110).
The following table shows class C IP address last octet values for each subnet.
The following table is a summary for class “C” subnet planning.
Subnetting With Class A and Class B Networks.
For class “A” and class “B” addresses the subnet mask also determines which bits are part of
the network number and which are part of the host ID.
A class “B” address has two host ID octets available for subnetting and a class “A” address has
three host ID octets (
) available for subnetting.
Table 238 Eight Subnets
SUBNET SUBNET ADDRESS FIRST ADDRESS LAST ADDRESS BROADCAST ADDRESS
1
0
1
30
31
2
32
33
62
63
3
64
65
94
95
4
96
97
126
127
5
128
129
158
159
6
160
161
190
191
7
192
193
222
223
8
224
223
254
255
Table 239 Class C Subnet Planning
NO. “BORROWED” HOST BITS SUBNET MASK
NO. SUBNETS
NO. HOSTS PER
SUBNET
1
255.255.255.128 (/25)
2
126
2
255.255.255.192 (/26)
4
62
3
255.255.255.224 (/27)
8
30
4
255.255.255.240 (/28)
16
14
5
255.255.255.248 (/29)
32
6
6
255.255.255.252 (/30)
64
2
7
255.255.255.254 (/31)
128
1