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RFC 1982 / SERIAL NUMBER ARITHMETIC

Track the whole increment history

04

Each small step may advance while its final endpoint is older than, undefined against, or equal to an earlier starting point.

RFC 1982 · § 4EXAMPLE
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Track the whole increment historyChosen chain0 to100 to200 to0 uses defined increments100,100,56. The third endpoint equals the original despite every individual step advancing relative to its own start.Inspect the whole increment historyChosen eight-bit chain · three allowed increments0+100100+100200+560Every step advances relative to its predecessorFinal 0 EQUALS the original 0No original-start order follows from step countRFC1982 · chapter 4 · state 4 · offline examples
04
Return to the original label

The third increment is 56. All three individual steps advance, but the final label equals the original; no original-start relationship follows just from the step count.

Source for this drawing: RFC 1982 · Read RFC section 4 ↗

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KEY POINT

Newer than the immediately previous value does not imply newer than every earlier value.

  • Corollary 1: a defined increment produces a serial greater than or equal to its start, equal only for zero. Corollary 2: after a nonzero defined n and another defined m, no general older/newer conclusion follows relative to the original start, although the result is known not equal to it (§§4.1–4.2). This is a limit on a general inference, not a claim that every particular endpoint comparison is undefined.
  • The published eight-bit chain 100→200→44 adds 100 twice. Each new serial is greater than its immediate predecessor, yet 44 is less than the original 100. In fact 100<200,200<44,44<100 forms a cycle under serial comparison. Sorting every possible serial as if this were an ordinary transitive comparator is unsound (§§3.2,4.2,5.2).
  • Two defined increments of 64 from zero reach 128, an undefined comparison against zero. In contrast 0→60→120 has total increment 120 within the allowed 127 limit: Corollary 4 guarantees the final result is greater than the start. A small per-step increment alone is insufficient; the sum matters (§§4.2,4.4).
  • Corollary 3 says a further increment leaves no generally known relationship to the original start. Chosen chain 0→100→200→0 uses increments 100,100,56, all individually defined; the last endpoint equals the original. These are offline arithmetic examples, not a prescribed DNS reset procedure (§4.3).
DETAILS

Fictional offline arithmetic and DNS observations. Small spaces illustrate the rule; DNS SOA uses 32 bits. Not a DNS implementation, transfer protocol, operational reset recipe or authenticity check.

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