subnetting
Hello all,
I am a little confused about subnetting. I read an article
in the linux journal. I later bought a book and it seems to
give quite a different picture of subnets.
First a quote from the book:
Debian GNU/Linux 2.1 Unleashed
----snip-----
When subnetting, it's important to note that the subnetworks
that have the address with all zeros and all ones are invalid.
So, in the previous example where we divided the 8-bit host
address into a 3-bit subnet address and 5-bit subnet address,
we will only be able to have 6 subnetworks instead of the 8 that
we might have expected because '000' and '111' are invalid
subnetwork addresses...
Table 16.2 Subnets inside a Class C Network
Netmask Usable Subnets Hosts per Subnet Total Hosts
255.255.255.0 1 254 254
255.255.255.128 0 127 0
255.255.255.192 2 62 124
255.255.255.224 6 30 180
255.255.255.240 14 14 196
255.255.255.248 30 6 180
255.255.255.252 62 2 124
255.255.255.254 127 0 0
----snip-----
As far as I understood the following is correct.
Netmask Usable Subnets Hosts per Subnet Total Hosts
255.255.255.128 2 126 252
255.255.255.192 4 62 248
255.255.255.224 8 32 240
255.255.255.240 16 14 224
255.255.255.248 32 6 192
255.255.255.252 64 2 128
I haven't needed to worry about such matters in practice, but I
wanted to know which is correct.
t:irvine
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