for the network ID, and the rest of the bits, 8, are
reserved for the hosts. In order to create 8 subnets out of
the original 1, 3 bits (2 = 8) would have to be borrowed
from the host portion and dedicated to the new network
IDs. The subnet mask in this case changes as follows:
Original subnet mask: 11111111.11111111.11111111.00000000 (/24)
New subnet mask: 11111111.11111111.11111111.11100000 (/27)There are still 5 bits left for hosts on each subnet, which
results in 2 = 32 − 2 (1 reserved for the network address
and 1 reserved for the broadcast address) = 30 usable IP
addresses for each subnet. This is more than needed to
accommodate the 20 devices for each department. The
new subnets look like those shown in Table 16-6; each
one has a /27 mask:
Table 16-6 Creating Additional Subnets from
192.168.0.0/24Subn
etNetwork
AddressBroadcast
AddressAvailable Host Address
RangeSubn
et 1192.168.0
.0192.168.0
.31192.168.0.1 to
192.168.0.30Subn
et 2192.168.0
.32192.168.0
.63192.168.0.33 to
192.168.0.62Subn
et 3192.168.0
.64192.168.0
.95192.168.0.65 to
192.168.0.94Subn
et 4192.168.0
.96192.168.0
.127192.168.0.97 to
192.168.0.126Subn
et 5192.168.0
.128192.168.0
.159192.168.0.129 to
192.168.0.158Subn
et 6192.168.0
.160192.168.0
.191192.168.0.161 to
192.168.0.19035