Homework on Stale Blocks

Blockchain and Bitcoin 101
#802

You get two different blockchains propagated in the network. Both are valid and you get two versions of the truth which are competing against each other. Each node decides by its own which is the valid chain (from its current state of knowledge). The simple rule is that the blockchain with the highest Work wins the competition. The total Work is calculated based on the difficulty (more precise : the target). Practically this is the chain with the most blocks.

A stale block is a valid block added to the blockchain that was finally ignored/dropped/discarded by the network.

Stale blocks occur when a node decides that another blockchain is “stronger” - has more PoW ( generally when the other blockchain is longer). All blocks that were newly added (so different from the new blocks added to the “stronger”) become stale blocks.

It reduces the risk that the block, your transaction is in, will become a stale block. When this happens, your transaction is not in the blockchain any more (because it was in the “wrong” one). The more blocks you wait the more sure you can be that your transaction is in the “right” blockchain.

1 Like
#803

They get selected by the next miner creating the next block with their block that makes the longest blockchain.

Stale block is block added to the mempool.

By adding more blocks from different miners before next block (longest blockchain) is accepted by whole network.

Six blocks or approximately 10min is needed for block to be accepted by whole network . i guess.

#804

But here we mean that you should wait for more confirmations to be sure that you transaction is immutable forever on the blockchain. With 1 confirmation, there is a chance that your transaction was mined in a stale block.
After 6 confirmations, you can be sure that your transaction is forever on the blockchain

1 Like
#805

It doesn’t check wich chain is longer after 6 confirmations. The 6 confirmations is for users wo send a transaction. If you wait for 6 confirmations, you will be sure that your transaction will be on the blockchain forever.

When 2 miners mine a block at the same blockheight, there will be 2 versions of truth (2 different blockchains) then it depends on wich version the next miner successfully mines a new block on top of it. This will make 1 version (blockchain) longer than the other. The transactions that were in that block of the shorter chain will go back to the mempool. (if they weren’t already included in the other version)

#806

Not the nonce must be lower than target, but the entire blockhash. Because hashing new info is so unpredictable, it’s hard to get a hash starting with a bunch of zero’s. To achieve this, you need to find a random number (nonce) that will produce a blockhash low enough.

1 Like
#807
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    One of them, (the most advanced one), will win and connect to the blockchain, the other one, (the stale=orphane one), will lose and be sent back to the mempool again).
  2. What is a stale block?
    A stale block is the losing part of the fork, and will transferred back to mempool.
  3. How do stale blocks occur?
    Occurs when 2 miners, often in diff. parts of the world, are working on the same block. They both have valid nonces and TX’s at the time and a fork is made, one will be put on winning chain and the stale block loses.
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Because of the above, you want to be sure your TX’s are accepted on the valid block and not end up on the orphane. Waiting for 6 confirmations is best, the network will sync approx. every 10 mins.
#808

It doesn’t check wich chain is longer after 6 confirmations. The 6 confirmations is for users wo send a transaction. If you wait for 6 confirmations, you will be sure that your transaction will be on the blockchain forever.

When 2 miners mine a block at the same blockheight, there will be 2 versions of truth (2 different blockchains) then it depends on wich version the next miner successfully mines a new block on top of it. This will make 1 version (blockchain) longer than the other. The transactions that were in that block of the shorter chain will go back to the mempool. (if they weren’t already included in the other version)

#809

You’re a legend Fabrice. Thank you

Den lör 23 maj 2020 15:21Fabrice Manzo via Ivan on Tech Forum <[email protected]> skrev:

1 Like
#810
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    they split into 2 blockchains and the next block will choose in which blockchain it wants to be and the
    other block will then be cancelled.
  2. What is a stale block?
    a block that got dropped because it didn’t have the longest blockchain.
  3. How do stale blocks occur?
    when 2 blocks go through the network atthe exact same thime and they split into 2 versoins and the
    next block will choose which version it wants to build on and the other block gets cancelled and is
    then called a stale block.
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a
    transaction?
    to make sure that your block isn’t a stale block and doesn’t get cancelled.
#811
  1. when they solve a block at the same time those two blocks “compete” to stay in the blockchain wanting miners to continue on one of those blocks.
  2. stale block- block that was once in the blockchain but isnt anymore because it was dropped(belonged to a shorter chain)
  3. A block becomes a stale block when it was mined and not used in the chain because it was mined prior to the 10mis, or was competing with another block to stay in the chain or didnt survive the 6 confirmation blocks
  4. For being sure that the transaction is saved in the main chain and wasnt dropped back to the memepool
#812
  1. Blockchain splits in two until one chain wins with amount of new blocks and become longer
  2. Blocks that been dropped from the chain that lost, became shorter than the other one
  3. When chain splits in two and one of the blockchain wins, the one that lost has a blocks that are dropped - called stale blocks
  4. Just so if chain split occurs you not ending up in the one that will lose the battle
#813
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    The miner with more network connections to the bitcoin network will get it. As I understand it the miner with at least 3 other nodes confirming with miner 1, will most likely be the one to be added.
  2. What is a stale block?
    A stale block is a block that was at one time being confirmed but time and confirmation created a situation where longer more higher fees block were accepted first.
  3. How do stale blocks occur?
    Time and confirmation create stale blocks, miners collect and bundle tx’s within the 10-minute rule (the fixed “block time” of Bitcoin) into blocks. The computers then compete to solve a complex cryptographic puzzle to be the first to validate the new block for the blockchain, those not added create stale blocks. Tx’s go back into the mempool.
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    For the security reason of double-spending. A tx should be confirmed by previous blocks (at least 3) to have condidence in tx be added to the blockchain.
#814

  1. The network will choose the longest chain, meaning that if a third miner were to complete their block off of one of the two miner’s block, the network will choose the longer chain and the the other block will be dropped

  2. Blocks that were in the chain at one point but got dropped back into the mempool

  3. Stale blocks occur when miners complete a block at the same time

  4. You should wait for 6 confirmations to ensure that your transaction will be processed

#815

I’m not a legend lol,
I’m just a simple monkey :monkey:
I’m just trying to help others & I’m trying to learn more during the process :v:

1 Like
#816

What happens in the bitcoin network when two miners solve a block at the same time?
for a short time, there will be 2 valid ends.

  • What is a stale block?
    A dropped block thanks to earlier block was produced at the same time as another miners block.

  • How do stale blocks occur?
    block was produced at the same time from more than one miner.

  • Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    to confirm that your block wont be dropped and your transaction will be sended back to mempool.

#817

one group of nodes will carry the blockchain at the end and another group will carry it to another end

a stale block is a block that doesn’t end up in the blockchain in the finally

stale blocks happen when two blocks are mined at the same time but this doesn’t happen very often

because the chance of a block being stale doesn’t increase the more blocks being added after it

1 Like
#818

1 Given the case where there are 2 blocks solved at the same time,a fork will be created temporarily and the block in the longest chain will be maintained while the other block is discarded (stale/orphaned block).

2/3 A stale block is a deleted/discarded block because a longer chain has been created in another block created at the same time.

4 It is important to wait (6 confirmations) so we can be sure that our transaction is registered in a block that has not been discarded in the meantime.

1 Like
#819

What happens in the bitcoin network when two miners solve a block at the same time?
While both blocks are true, only one will be accepted. The block is built on the quickest, creating the longer string, will be recognized by the chain. The other block is considered stale and the transactions in that block will return to the mempool.

What is a stale block?
A stake or orphaned block, while true, is on the shortest string and thus not recognized by the blockchain.

How do stale blocks occur?
It is possible for two versions of the same block to be produced. One of those two blocks will be accepted- the block that is built upon faster. The other will be considered orphaned and the transaction within the orphaned block are returned to the mempool.

Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
There is a chance that the block can become stale if a fork occurred. The 10 minute block difficulty will take care of a fork, as only the longest string is recognized. One version of the block will be accepted, while the other will be considered stale and removed from the blockchain.

1 Like
#820

What happens in the bitcoin network when two miners solve a block at the same time?

These blocks may propagate via different routes and get added by different nodes. This has become an issue because now there are two versions of truths, and one of the two blocks will get discarded if it is not in the longest chain.

What is a stale block?

A valid block that is removed by nodes for lack of adequate confirmations

How do stale blocks occur?

A stale block happens when a block gets discarded from nodes because the nodes see that there is another chain that is longer without this block.

Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?

The block that get at least 6 blocks behind it has a good chance of being kept permanently

1 Like
#821

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    Their is basically 2 versions of the blockchain temporarily until 1 of them mines their next block. That longer chain becomes the true chain and the other block is dropped back to the mempool.

  2. What is a stale block?
    A stale block is a block that was successfully mined but was then dropped due to another version of the blockchain mining the next block faster. all those TXs go back to the mempool

  3. How do stale blocks occur?
    Stale blocks occur when two miners mine a block at the same time. Then they are basically in limbo until a miners adds to one of them. The longer chain wins and the shorter is dropped.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?Your TX could be in a block that may be dropped. At that point it wont truly be confirmed. Typically with bitcoin you want to wait 6 blocks to be sure.

1 Like