Ccna routing and Switching Complete Study Guide

The subnet address

0

32

64

96

128

160

192

224

The first valid host

1

33

65

97

129

161

193

225

The last valid host

30

62

94

126

158

190

222

254

The broadcast address

31

63

95

127

159

191

223

255

In practice example #3C, we’re using a 255.255.255.224 (/27) network, which pro-

vides eight subnets as shown previously. We can take these subnets and implement them as 

shown in Figure 4.5 using any of the subnets available.

f i g u r E   4 . 5     Implementing a Class C /27 logical network

192.168.10.128

.129

Router#show ip route

 [output cut]

C 192.168.10.0 is directly connected to Ethernet 0

C 192.168.10.32 is directly connected to Ethernet 1

C 192.168.10.64 is directly connected to Ethernet 2

C 192.168.10.96 is directly connected to Serial 0

.161

.98

.97

192.168.10.0

192.168.10.160

192.168.10.96

192.168.10.32

.33

.65

.1

192.168.10.64

Notice that used six of the eight subnets available for my network design. The lightning 

bolt symbol in the figure represents a wide area network (WAN) such as a T1 or other 

serial connection through an ISP or telco. In other words, something you don’t own, but it’s 

still a subnet just like any LAN connection on a router. As usual, I used the first valid host 

in each subnet as the router’s interface address. This is just a rule of thumb; you can use any 

address in the valid host range as long as you remember what address you configured so 

you can set the default gateways on your hosts to the router address.