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As I understand it, the terms Classless Inter-Domain Routing (CIDR) and Variable-Length Subnet Masking (VLSM) effectively refer to the same thing. Is there any noteworthy difference between the proper definitions of these terms? What is the history or relation between the two?

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marked as duplicate by masegaloeh, Michael Hampton Aug 27 '15 at 2:55

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

read this How does Subnetting Work?

I believe it is explain in one of the answers there.

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yes indeed, it is there for certain, hopefully that sets you straight. – SpacemanSpiff Feb 16 '11 at 4:54
Thanks for the link, but could you actually include the appropriate content in your answer? – Iszi Feb 18 '11 at 6:06

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