BitcoinTalk

Re: checkpointing the block chain

394
From:
satoshi
Subject:
Re: checkpointing the block chain
Date:
There is no way for the software to automatically know if one chain is better than another except by the greatest proof-of-work.  In the design it was necessary for it to switch to a longer chain no matter how far back it has to go.

The only exception to that is the manual checkpoints I've added.  If it weren't for those, it would be able to reorg all the way back to the first block.