<p>Each full-node checks the validity of blocks. Checking the validity of a block is indeed done by repeating all steps of building that block and checking for adherence to all consensus rules. If a block infringes any rule, a full-node will consider the block invalid, ignore the block, and ban the node that sent it to him from his peers for 24h for sending invalid information.</p>

<p>As each miner should be running a full-node to stay abreast of the current blockchain-tip, either all miners or no miners should consider a block valid (as long as they are in agreement on the consensus rules that apply).</p>

CC BY-SA 3.0
2017-03-27T23:53:54.837Z
Just want to confirm one thing, I suppose the block validation is done after the block was mined by a miner, but once the block is rejected by the maximum full nodes, then the blockchain with that block leading is ignored and a new valid block is mined by another full node, and then the valid block will lead the blockchain, until another block is added above it.
Imran Makhdoom
CC BY-SA 3.0
2017-03-28T00:15:36.880Z
I'm not sure that I understand your question, but every node _independently_ checks validity of blocks and ignores invalid blocks, invalid blocks don't get created usually.  If they do get created  they don't get seen by most of the network, as they don't get relayed.
Murch
CC BY-SA 3.0
2017-03-27T13:46:52.450Z
2017-03-27T13:46:52.450Z
Murch
<blockquote>
  <p>A new block is added to blockchain if more than 50% of miners say that
  it is solved correctly.</p>
</blockquote>

<p>wrong. you can not caclulate the percentage. you can either accept block to your chain or reject it</p>

CC BY-SA 3.0
2017-03-27T06:34:56.080Z
If other nodes / miners in the network simply accept or reject it, then there is suppose to be a threshold whether in number or in percentage that decides, whether block is to be added to chain or rejected.
Imran Makhdoom
CC BY-SA 3.0
2017-03-27T08:07:27.720Z
you can not caclulate the percentage. you can either accept block to your chain or reject it
amaclin
CC BY-SA 3.0
2017-03-27T06:00:46.510Z
2017-03-27T06:00:46.510Z
amaclin
<p>A new block is added to blockchain if more than 50% of miners say that it is solved correctly. Does it mean that all other miners also do the same proof of work by including the same transactions as in the broadcasted block, and same nounce, as used by the miner of latest block?</p>

<mining-theory><bitcoin-core-development>
Validation of a new block
Imran Makhdoom
# Validation of a new block

(Asked by: username_0 on 2017-03-27)

A new block is added to blockchain if more than 50% of miners say that it is solved correctly. Does it mean that all other miners also do the same proof of work by including the same transactions as in the broadcasted block, and same nounce, as used by the miner of latest block?

**Tags:** mining-theory, bitcoin-core-development


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## 2 answers

### Answer by username_1 on 2017-03-27. Score: 1 | Accepted answer

Each full-node checks the validity of blocks. Checking the validity of a block is indeed done by repeating all steps of building that block and checking for adherence to all consensus rules. If a block infringes any rule, a full-node will consider the block invalid, ignore the block, and ban the node that sent it to him from his peers for 24h for sending invalid information.

As each miner should be running a full-node to stay abreast of the current blockchain-tip, either all miners or no miners should consider a block valid (as long as they are in agreement on the consensus rules that apply).

> **Comments:**
> **username_0**: Just want to confirm one thing, I suppose the block validation is done after the block was mined by a miner, but once the block is rejected by the maximum full nodes, then the blockchain with that block leading is ignored and a new valid block is mined by another full node, and then the valid block will lead the blockchain, until another block is added above it.  
> **username_1**: I'm not sure that I understand your question, but every node _independently_ checks validity of blocks and ignores invalid blocks, invalid blocks don't get created usually.  If they do get created  they don't get seen by most of the network, as they don't get relayed.  

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### Answer by username_2 on 2017-03-27. Score: 0

> A new block is added to blockchain if more than 50% of miners say that
> it is solved correctly.

wrong. you can not caclulate the percentage. you can either accept block to your chain or reject it

> **Comments:**
> **username_0**: If other nodes / miners in the network simply accept or reject it, then there is suppose to be a threshold whether in number or in percentage that decides, whether block is to be added to chain or rejected.  
> **username_2**: you can not caclulate the percentage. you can either accept block to your chain or reject it  

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