<p>When there's a fork, part of the network will mine to find the next block in one branch and part in the other branch. Whichever part finds the next block first will determine the winning branch.</p>

<p>A miner who finds a block will want to spread it widely and quickly. This makes sure there are many other miners who saw his block first, and thus a high probability that the next block will be found by one of those.</p>

CC BY-SA 3.0
2013-04-10T19:24:29.000Z
Is there anything a miner can do to send his block out more quickly?  Or to disrupt other miners from sending out theirs?
Ben
CC BY-SA 3.0
2013-04-10T19:41:38.800Z
@Ben: Being connected to many nodes and having a fast internet connection could help. I don't know of ways to disrupt other miners.
Meni Rosenfeld
CC BY-SA 3.0
2013-04-10T19:42:08.770Z
Can anyone explain the downvote?
Meni Rosenfeld
CC BY-SA 3.0
2013-04-10T21:56:21.513Z
I am baffled by it.
Ben
CC BY-SA 3.0
2013-04-11T00:15:30.410Z
A block is first verified before it is relayed.  So a block with fewer transactions will be verified sooner than a block with many transactions.  However trying to limit that will cause fees to be missed, so there's an economic cost that offsets the economic gain.
Stephen Gornick
CC BY-SA 3.0
2013-04-11T03:46:52.480Z
Theoretically, miners could form a coalition that would agree to mine after each other's found blocks, even if the block was found later, so long as the chain was the same length. I doubt it would be worth the trouble, but it would give members of the coalition a slightly greater chance of winning against a block found by a miner not in the coalition.
David Schwartz
CC BY-SA 3.0
2013-04-11T06:57:34.700Z
@DavidSchwartz: This sounds like the mining cartel attack (https://bitcointalk.org/index.php?topic=2227.0;all). It requires the cartel to have at least ~40% of the total hashrate to work.
Meni Rosenfeld
CC BY-SA 3.0
2013-04-11T07:00:21.630Z
@MeniRosenfeld: Very similar. I'm suggesting a much weaker version -- mine from the longest chain in all cases, but break ties between a cartel member and a non member in favor of the cartel member regardless of which block was seen first.
David Schwartz
CC BY-SA 3.0
2013-04-11T11:08:34.087Z
@DavidSchwartz: Yeah, that is simpler.
Meni Rosenfeld
CC BY-SA 3.0
2013-04-10T19:18:35.223Z
2013-04-10T19:18:35.223Z
Meni Rosenfeld
<p>From my understanding, a SHA256 hash is generated by a miner and if the hash is less than a specific value, it is passed to its peers.  That said, It's possible for multiple hashes to be created at very close to the same time.  If this happens, how is the "winner" determined?  I see this has happened a lot (multiple orphaned blocks).  </p>

<p>What can be done by the miner to see that their block wins the race, either honestly or through an attack?  The protocol stipulates that the block shall be recognized by which ever was received first.  Is it advantageous to set up peering with other miners? </p>

<blockchain><blockchain-fork><stale-block>
Who wins the race for multiple valid blocks mined at the same time?
Ben
# Who wins the race for multiple valid blocks mined at the same time?

(Asked by: username_0 on 2013-04-10)

From my understanding, a SHA256 hash is generated by a miner and if the hash is less than a specific value, it is passed to its peers. That said, It's possible for multiple hashes to be created at very close to the same time. If this happens, how is the "winner" determined? I see this has happened a lot (multiple orphaned blocks).

What can be done by the miner to see that their block wins the race, either honestly or through an attack? The protocol stipulates that the block shall be recognized by which ever was received first. Is it advantageous to set up peering with other miners?

**Tags:** blockchain, blockchain-fork, stale-block


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## 1 answers

### Answer by username_1 on 2013-04-10. Score: 9

When there's a fork, part of the network will mine to find the next block in one branch and part in the other branch. Whichever part finds the next block first will determine the winning branch.

A miner who finds a block will want to spread it widely and quickly. This makes sure there are many other miners who saw his block first, and thus a high probability that the next block will be found by one of those.

> **Comments:**
> **username_0**: Is there anything a miner can do to send his block out more quickly?  Or to disrupt other miners from sending out theirs?  
> **username_1**: @username_0: Being connected to many nodes and having a fast internet connection could help. I don't know of ways to disrupt other miners.  
> **username_1**: Can anyone explain the downvote?  
> **username_0**: I am baffled by it.  
> **username_2**: A block is first verified before it is relayed.  So a block with fewer transactions will be verified sooner than a block with many transactions.  However trying to limit that will cause fees to be missed, so there's an economic cost that offsets the economic gain.  
> **username_3**: Theoretically, miners could form a coalition that would agree to mine after each other's found blocks, even if the block was found later, so long as the chain was the same length. I doubt it would be worth the trouble, but it would give members of the coalition a slightly greater chance of winning against a block found by a miner not in the coalition.  
> **username_1**: @username_3: This sounds like the mining cartel attack (https://bitcointalk.org/index.php?topic=2227.0;all). It requires the cartel to have at least ~40% of the total hashrate to work.  
> **username_3**: @username_1: Very similar. I'm suggesting a much weaker version -- mine from the longest chain in all cases, but break ties between a cartel member and a non member in favor of the cartel member regardless of which block was seen first.  
> **username_1**: @username_3: Yeah, that is simpler.  

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