Sorry to throw in a big text-graphic. I couldn't think of a better way to create this in plain text and html.
An IPv6 address is 128 bits. This is to help me organize and remember subnets and blocks(aka. doctet, quartet,chazwazza, etc.).
In any event, the usual pattern is to have the first three blocks (ABC's) assigned by an internet provider out of their allocation. The "d's" are usually the subnet that gets assigned to an organization. Depending on size, an org may be assigned/awarded a /48 or /56. I remember the d block as the bits usually available for subnetting by thinking of deltas. I can't explain why that makes sense to me. I number the last four blocks (4:3:2:1) to separate out that those are host bits.
The CCENT guidedtnes state six IPv6 Address types to know for the exam.
last updated May 2015
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