Is extranonce sometimes necessary for blocking?

Question

Is extranonce ever necessary to find a block, e.g., in cases where exhausting the regular nonce range fails to block? Is this the rationale behind extranonce?

I don't think "blocking" is a term ever used for "creating blocks". — Jannes, May 19 '15 at 08:20
@Jannes I've seen it used that way before, but I don't know how established that terminology is. — Geremia, May 20 '15 at 04:17

score 1 · Accepted Answer · answered May 18 '15 at 19:23

Yes, it's almost always necessary. The current Bitcoin difficulty is 48,807,487,245, which means (approximately) that if you go through all possible values for the regular 32-bit nonce, your probability of finding a valid proof of work is only 1 in 48,807,487,245. So the vast majority of times, you will exhaust all possibilities for the regular nonce, at which point you can increment the extraNonce and continue.

Is extranonce sometimes necessary for blocking?

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