166
Chapter 3
Internet Protocols
Broadcast address for each subnet?
Valid hosts?
The following table shows some examples of the host ranges--the first,
second, and last subnets:
Practice Example #3A: 255.255.255.192 (/26)
Let's do one more example using the second, third, and fourth octets for
subnetting.
Subnets? 2
18
- 2 = 262,142.
Hosts? 2
6
- 2 = 62.
Valid subnets? Okay, now we need to add subnet numbers from the
second, third, and fourth octets. In the second and third, they can
range from 0 to 255, as long as all subnet bits in the second, third, and
fourth octets are not all on at the same time. For the fourth octet, it
will be 256
- 192 = 64. And 0 will be valid as long as at least one other
subnet bit is turned on in the second or third octet. Also, 192 will be
valid as long as all the bits in the second and third octets are not
turned on.
Broadcast address for each subnet?
Valid hosts?
The following table shows the first few subnets and their valid hosts and
broadcast addresses in the Class A 255.255.255.192 mask:
Subnet
10.1.0.0
10.1.16.0
...
10.255.224.0
First host
10.1.0.1
10.1.16.1
...
10.255.224.1
Last host
10.1.15.254
10.1.31.254
...
10.255.239.254
Broadcast
10.1.15.255
10.1.31.255
...
10.255.239.255
Subnet
10.0.0.64
10.0.0.128
10.0.0.192
10.1.0.0
First host
10.0.0.65
10.0.0.129
10.0.0.193
10.1.0.1
Last host
10.0.0.126
10.0.0.190
10.0.0.254
10.1.0.62
Broadcast
10.0.0.127
10.0.0.191
10.0.0.255
10.1.0.64
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