<p>Each node will usually resolve and reorganize their local chain as soon as they are made aware of a chain with more work.</p>
<p>If two blocks are mined at block height <code>N</code>, there is a fork. As soon as a single block at height <code>N+1</code> is mined and broadcasted, any nodes that receive it will keep the block <code>N</code> that the new block builds upon, and orphan the other block as there is now one chain with more work.</p>
<p>This is what makes block withholding attacks possible, as an attack could broadcast several blocks at once, which suddenly present a new, longer, valid chain.</p>

CC BY-SA 4.0
2018-09-28T04:35:40.903Z
That is assuming that the miners are honest right? If let's say a group of miners are colluding, can they withhold from resolving until they are sure that their chain is longer?
Larrrrrrrrrry
CC BY-SA 4.0
2018-09-28T04:36:38.267Z
Yes, that's exactly what a block withholding attack is - One or more miners don't broadcast their blocks until they want to, and broadcast entire sections at once
Raghav Sood
CC BY-SA 4.0
2018-09-28T23:11:38.363Z
It really shouldn't be called an "orphan" block, because the block's parent is present and doing fine. ;) It's the transactions in the _extinct_ block or stale chain-tip that are orphaned by the block no longer being part of the most-work chain.
Murch
CC BY-SA 4.0
2018-09-28T04:29:02.397Z
2020-11-30T21:50:07.217Z
2020-11-30T21:50:07.217Z
Raghav Sood
<p>I understand that forks are resolved by largest proof-of-work etc. but when do the miners decide to resolve a fork? Is it a question of network consensus or does each individual miner resolve at their own pace?</p>

<blockchain-fork><best-chain>
When does a blockchain fork resolution happen?
Larrrrrrrrrry
# When does a blockchain fork resolution happen?

(Asked by: username_0 on 2018-09-28)

I understand that forks are resolved by largest proof-of-work etc. but when do the miners decide to resolve a fork? Is it a question of network consensus or does each individual miner resolve at their own pace?

**Tags:** blockchain-fork, best-chain


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## 1 answers

### Answer by username_1 on 2018-09-28. Score: 2 | Accepted answer

Each node will usually resolve and reorganize their local chain as soon as they are made aware of a chain with more work.

If two blocks are mined at block height `N`, there is a fork. As soon as a single block at height `N+1` is mined and broadcasted, any nodes that receive it will keep the block `N` that the new block builds upon, and orphan the other block as there is now one chain with more work.

This is what makes block withholding attacks possible, as an attack could broadcast several blocks at once, which suddenly present a new, longer, valid chain.

> **Comments:**
> **username_0**: That is assuming that the miners are honest right? If let's say a group of miners are colluding, can they withhold from resolving until they are sure that their chain is longer?  
> **username_1**: Yes, that's exactly what a block withholding attack is - One or more miners don't broadcast their blocks until they want to, and broadcast entire sections at once  
> **username_2**: It really shouldn't be called an "orphan" block, because the block's parent is present and doing fine. ;) It's the transactions in the _extinct_ block or stale chain-tip that are orphaned by the block no longer being part of the most-work chain.  

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