ThetaCorp has been assigned three class C network addresses: 220.127.116.11, 18.104.22.168 and 22.214.171.124. You want to combine these addresses into one logical network to increase the number of hosts IDs you can have on your company's network. Which subnet mask must you use?
As its name suggests, supernetting, officially called Classless Interdomain Routing (CIDR), is the inverse of subnetting. When you create a subnet, you break a network ID into subnets; when you create a supernet, you create a larger logical network ID from several smaller network IDs.
In subnetting, you operate on the highest (leftmost) host ID octet, the fourth octet for a class C address. In supernetting, you work on the lowest (rightmost) net ID octet, the third octet for a class C address. Taking the class C addresses 126.96.36.199, 188.8.131.52 and 184.108.40.206 as our example, we convert them into binary:
220.127.116.11 = 11010000.11001001.00000100.00000000 18.104.22.168 = 11010000.11001001.00000101.00000000 22.214.171.124 = 11010000.11001001.00000110.00000000
Seen in binary, we notice that only the last two digits of the third
octet differ (00, 01 and 10).
Therefore, we can safely mask the preceding digits with the supernet
mask 255.255.252.0 (11111111.11111111.11111100.00000000), leaving
the ten-digit addresses 0000000001 through 1111111110 for a continuous
range of host IDs.
Before attempting to implement supernetting,
remember that your routers must also support CIDR.
Your company has been assigned three class C network addresses: 126.96.36.199, 188.8.131.52 and 184.108.40.206. You want to combine these addresses into one logical network to increase the number of hosts IDs you can have on your company's network. Which subnet mask must you use?
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