Class A 0 0.0.0.0
Class B 10 128.0.0.0
Class C 110 192.0.0.0
Class D 1110 224.0.0.0
Class E 1111 240.0.0.0
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以上取自WIKI~
http://en.wikipedia.org/wiki/Classful_network
沒事看WIKI ~ 看WIKI沒事~