Homework on Stale Blocks

Blockchain and Bitcoin 101
#141

Stale Blocks - Questions

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

Two versions of the blockchain will exist and spread throughout nodes, where some nodes will see one one chain as the real one and others will see the other chain as the real one.

  1. What is a stale block?

A block that was once considered part of the blockchain but then is ignored because another longer chain is recognized as true by the network.

  1. How do stale blocks occur?

In the situation of question 1, if one of the blockchains then adds another block before the other, the longer chain will be accepted as the true blockchain and the other block will be ignored and considered “stale” or “orphaned”.

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

In the situation of question 1, the transaction is considered “confirmed” for one block but then becomes unconfirmed once the block becomes stale. This means the sender could potentially “cancel” or double spend the transaction in this scenario, so if a sale was made contingent on only the first confirmation, the sender could receive the product as well as double spend. (I think this is possible I’m not 100% sure, regardless it is good to wait for true confirmation)

#142
  1. When the two miners are the same they wait in the forks temporarily.
  2. A stale block is when they are put back in the mempool.
  3. Stale block occur when a fork is resolved with a longer chain length .
  4. The transaction could be in the stale block, the chain wont be used and goes back to the mempool.
#143

What happens in the bitcoin network when two miners solve a block at the same time?
The chain becomes forked temporarily.
What is a stale block?
An alternative truth for the future, proof of work determines the truth that survives, the other one becomes a stale block, that gets discarded and orphaned by the network
How do stale blocks occur?
When the blockchain forks because two miners solved a block at the same time, the network of nodes will choose the chain with the most proof of work. The stale block returns to the mempool
Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
To be ensured it doesn’t turn out to be a stale block. In bitcoin it’s recommended to wait for six blocks to get confirmed to validate a transaction

#144
  1. Then you have 2 versions of the truth
  2. Stale block - a block that is dropped from the blockchain.
  3. When there is a “true” block that is not chosen by a new miner’s pow.
  4. To ensure your transaction isn’t dropped (becomes stale).
#145
  • When 2 miners solve a block at the same time the block in the longest chain wins and the other block is discarded and considered a stale or orphaned block. All the transactions are returned to the mempool.
  • A stale block is the block that was in the blockchain but then dropped because another block that was produced at the same time was part of a longer chain.
  • Stale blocks occur when a block was valid for a while because 2 were produced with the same version of the truth but then dropped because the blockchain continued on another block.
  • It is important to wait for 6 confirmations to be sure that the block your transactions are in is not dropped from the chain.
#146
  1. The network picks the longer blockchain, so one of the blocks might end as stale.
  2. A block that was dropped by the blockchain. All the transactions will go back in the mempool.
  3. Stale blocks occur when two miners mine a valid block at the same time.
  4. You will get the latest version of the blockchain.
#147

Question 1

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

When 2 miners solve a block at the same time they each transmit the blocks to the nodes nearest to them. At this moment there are 2 versions of the truth propagating around the network. The network must then wait for a confirmation to reach consensus.

Question 2

What is a stale block?

A stale block is a valid block but not the longest block in the chain so it gets discarded and the transactions in it get returned to the mempool

Question 3

How do stale blocks occur?

Stale blocks occur if the difficulty is too low and when there are 2 chains competing to add a block to the chain. A block becomes a stale block when it is the shortest block in the chain.

Question 4

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

It is important to wait for more than one block to be confirmed because in the unlikely event that your transaction is in a block which may be the shortest in a chain/orphaned block then the more confirmations the more likely the transaction was successful and it is truly on a chain.

#148
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    there are 2 blockchain versions exists in parrallel on the network. both are true at that time
  2. What is a stale block?
    A block that has been valid, but than set to unvalid because another chain gets “longer” and being validated as the truth (only valid version of the blockchain)
  3. How do stale blocks occur?
    If 2 miners creates blocks at the same time
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    To be sure that the transaction will not be set to unconfirmed and put back into the mempool, because the block would be set to be a stale block
#149

1-When two miners solve block at the same time the block splits in two. Nodes do not recognize this event until another miner makes a longer block. The shorter block becomes stale with the transactions returned to MEM pool. All nodes get longer block transactions and are finally in agreement.
2-Stale block is shortest chain in a split block
3-Stale blocks occur when two miners mine a valid block at the same time
4-It is important to wait more than one block to be confirmed because it may be a stale block. It is recommended to wait for 6 blocks confirmations.

#150
  1. Two different versions of the truth are being circulated or relayed and two blocks are created at the same time
  2. They are blocks that are no longer part of the “current best” blockchain because they were overtaken by a longer chain.
  3. When two different miners relay their valid blocks almost at the same time, this causes the network to split into two competing versions of the chain.
  4. A transaction could be left Stale or Orphaned if it doesn’t have enough confirmations to secure it in the chain. 6 confirmations are recommended.
#151

  1. When two miners solve a block at the same time, the block will be placed with lonest chain. The other block will be considered a stale or orphaned block and then be placed back into the mempool.

  2. A stale block is a block that has been validated but was not used.

  3. A stale block happens when there is another block that has been mined at the same time. since they both are correct, there is only one version on the truth, and only the one with the longest chain wins.

  4. To be sure your block has not been forked, or not turned stale, you must wait until 6 new blocks have been added to the chain.

#152

1 The block chain forks.
2 A stale block is a block that is not excepted on the chain.
3 Stale blocks occur when another block that is longer is accepted first.
4 To help minimize Stale Blocks or Orphaned blocks.

#153
  1. When two miners solve a block at the same time, there is a temporary split in the network as the solution(s) propagate throughout the network differently. This split however is resolved once a new block is crated (on one of the divergences), and the chain with the most POW is accepted as the verified network, at which point the other block is disregarded (stale block) and their tx return to the mempool.
    .
    .
  2. It is good practice to wait for 6 confirmations when engaging in tx, as this gives the network enough time to resolve any divergences and ensures your tx have been picked up in a block (and are not in stale/orphaned block).
#154
  1. Both blocks wil be appended to the latest block. This will result in two new chains. But the block in the
    chain with the highest POW wil remain. The other block will become stale.
  2. A block removed from the chain.
  3. This will occur when 2 blocks are added to the chain at same time.
  4. This is important to make sure that the transactions are not in a stale block.
#155

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    A split will happen in the chain (also called accidental split). This will be temporary until a newer block is appended to one of these split chains making it the longest chain.

  2. What is a stale block?
    Continuing previous answer, once the new longest chain is accepted by all nodes, the split block will be ignored. Hence creating a stale block.

  3. How do stale blocks occur?
    Explained in the 2 previous questions.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Because a block might become stale, making all transactions on it not not count. Once a few blocks are appended, chances of still having a split chain are almost none.

#156

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

Both blocks will be active.( Temporary Fork) Miners will start to mine the next block on either of the two blocks. Depending on which one of the blocks gets appended with the new block, will determine the longest chain and the other Block will get dropped or Orphaned.

What is a stale block?

It is a block that has been dropped or orphaned because another block has been accepted as part of the longer chain. The Transactions from the Orphaned block are put back into the mempool for the next blocks to incorporate them into their Block.

How do stale blocks occur?

When two blocks are valid at the same time with the same version of the truth, one block will eventually be stale due to the progressing on either one of the blocks as the truth and being the longest chain.

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

As discussed above, when two blocks with the same truth occur it is better to wait and see which block will continue the chain. Once the second confirmation is there it will tell you that the block has been accepted into the chain. To be absolutely sure, the accepted consensus for definitive confirmation is around 6 Confirmations. Although it is generally excepted when moving large amounts of crypto to wait till about 11 confirmations.

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#157

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

    • The next block that is solved may not contain both of those blocks. In that instance the longest block is chosen and the “Stale” or “Orphaned” block goes back into the mempool to be processed again.

  2. What is a stale block?

    • A block that may have not been included by the miner that validates the next block.

  3. How do stale blocks occur?

    • When a block does not have time to propagate through the network and another block is solved by a different miner. The longest POW (Proof of Work) is selected.

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

    • To verify the transaction has been accepted by the entire network.
#158

  1. The longest chain will win, the other one will eventually become a stale block.

  2. Stale blocks were blocks that were once dropped from the blockchain for longer ones.

  3. They occur when two miners mine a block at the same time and one advances because it has a longer block, the one that doesn’t becomes a stale block.

  4. So that the transaction can be confirmed with 6 confirmations, therefor it won’t drop from the chain.

#159
  1. What happens in the bitcoin network when two miners solve a block at the same time?
  • For a moment 2 versions of the blockchain will exist until another miner adds a new block to the chain based on V1 or V2. The longest chain will be the one approved by the network (the highest PoW) and continue forward, the TX that are in the rejected block will go back to the mempool. The rejected block is called Stale or Orphan block.
  1. What is a stale block?
  • A block that is not accepted in the network due to a time delay, its TX are returned to the mempool.
  1. How do stale blocks occur?
  • It can occur that 2 miners solve a block simultaneously, the one who has more PoW is the one who gets to add the block to the chain, and the rejected one is the stale block.
  1. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
  • To minimized the issue with stale blocks. We need to wait for at least 6 confirmations to be sure that our TX has been added to the chain.
#160

1.They both begin propagating out to the network.

  1. Stale (or orphan) blocks began to propagate but were later dropped because it was in effect a duplicate. As above, two miners solved the block at the same time. One must become the valid block. this is determined by comparing the blocks and picking the longest legitimate BC version.

  2. If a subsequent block is mined on one of the propagating chains it becomes the longer version and is determined to be the valid one.

  3. your transaction may be canceled and sent back to the mempool if it happens to be in an orphaned block.