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subnet mask 240 creates 14 subnets

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by northwood 1 view

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When subnettinga a class C IP address, adding a 240 subnett masks use to result in 14 subnet IDs. Now I hear that the subnet mask of 240 creates 16 subnet IDs. Is this true? If so, then why can 240 create up to 16 subnets instead of 14? Has the version of IP changed from version 4 to version 5?

4 replies

by bencheart18

240 creates 16 subnets IDs. It's true.

since the SM 240 is in 3rd octet, which is 20 bits from the leftmost or known as /20.

we have formula:

/20
/\
21 21 2 subnets
/\ /\
22 22 22 22 4 subnets
/\ /\ /\ /\
2323 2323 2323 2323 8 subnets
/\ /\ /\/\ /\ /\ /\ /\
2424 24 2424 2424.. .. .. 16 subnets

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