Subnetting with class a and class b networks – ZyXEL Communications P-660HW-T v2 User Manual
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P-660HW-T v2 User’s Guide
Appendix F IP Subnetting
303
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 (see
) available for subnetting.
The following table is a summary for class “B” subnet planning.
5
128
129
158
159
6
160
161
190
191
7
192
193
222
223
8
224
225
254
255
Table 142 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
Table 141 Eight Subnets (continued)
SUBNET
SUBNET ADDRESS FIRST ADDRESS
LAST ADDRESS
BROADCAST
ADDRESS
Table 143 Class B Subnet Planning
NO. “BORROWED” HOST
BITS
SUBNET MASK
NO. SUBNETS
NO. HOSTS PER
SUBNET
1
255.255.128.0 (/17)
2
32766
2
255.255.192.0 (/18)
4
16382
3
255.255.224.0 (/19)
8
8190
4
255.255.240.0 (/20)
16
4094
5
255.255.248.0 (/21)
32
2046
6
255.255.252.0 (/22)
64
1022
7
255.255.254.0 (/23)
128
510