Take the 2-minute tour ×
Bitcoin Stack Exchange is a question and answer site for Bitcoin crypto-currency enthusiasts. It's 100% free, no registration required.

I believe my two title questions are the same (are they?):

Heretofore, what is the longest chain of orphan blocks (of N blocks), such that if someone didn't wait for N+1 confirmations, they may have assumed transactions to be completed when they were not.

For example, on the wiki's blockchain article, it shows orphan chains of two blocks (N=2). In this case, 3 confirmations would have sufficed to confirm transaction with absolute accuracy. https://en.bitcoin.it/wiki/File:Blockchain.png

I ask because it seems 120 confirmations is the gold standard, if you will, as generated bitcoins take that long to confirm. Most other transactions are considered irrevocable at 6 blocks, but what has been the minimum, thus far?

PS. Is this question even answerable!?

share|improve this question
    
possible duplicate of What is the longest blockchain fork that has been orphaned to date? –  Thilo Jun 27 '12 at 5:20

2 Answers 2

up vote 4 down vote accepted

The longest orphaned fork was created due the "value overflow" bug occurrence, ranging from block 74638 to 74691 (so 53 blocks). Such a situation is unlikely to ever repeat though.

Other than that, as far as I remember 4 blocks were overwritten by some strange behaving miner (related question), but I might be mistaken.

In general, 6 confirmations is enough in most cases to prevent any double-spend attempts, and 120 confirmations is enough to give the developers time to release a fix for some major bug that might occur before the coin creation transactions are mixed in with everything else, creating a big mess.

share|improve this answer

Yes, the question is answerable, although it might be hard to get the data to answer it (you would need blockchains from a few very long-running, well-connected nodes that contained both the main chain and orphan chains).

I don't know the answer. As ThePiachu says, the longest orphan chain was 53 blocks, but I don't think any confirmed-on-one-chain transactions ended up unconfirmed on the other chain-- I don't think there were any double-spends across those two chains.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.