Homework on Stale Blocks

Blockchain and Bitcoin 101
#782

What happens in the bitcoin network when two miners solve a block at the same time? The chain of blocks would potentially split into two versions of true but, since there can only be one blockchain and one truth, the version who first gets additional blocks attached to it and verified would be accepted as the best blockchain to use.

What is a stale block? Stale blocks are those successfully mined and valid blocks whose transactions were not realized because they were part of the version of truth which was not accepted as the longest.

How do stale blocks occur? Stale blocks are produced when multiple versions of truth compete on the network.

#783

[1] When two miners solve there own blocks at the same time, a fork is created in the blockchain with the two new blocks being attached to the end of the last block of the blockchain.

[2] A stale block is a dropped block.

[3] Stale blocks occur by the blockchain algorithm choosing the longest forked chain to keep alive. The blocks of the shorter chain are simply dropped and from then are referred to as stale blocks.

[4] It is important to wait for more than one block to be confirmed when sending or receiving a transaction to avoid the situation of a double spend (DS) and a stale block not in the receiver’s interest occurring. E.g. The payer does a DS, and a fork in the blockchain is produce by chance with one block having the transaction paying the payee, and the other block having a transaction paying back the payer. Then the blockchain system later makes the legit block a stale one therefore causing the payee to be cheated.

#784
  1. it happens that the next block solve will not continue with 2 blocks but olny with 1 of the two previously miners block solved.
    2.stale block are blocks which at some point are no more validate by the blockchain because the new blocks solved didnt follow in blockchain with the same version of those blocks.
  2. when there are 2 differents version of chain block in the blockchain, the longest one will continue in the network and the other version will be put out again in the mempool.
  3. because forks can take some blocks until the network knows which is the longest one to keep in the blockchain.
#785
  1. When two miners solve a block at the same time, they are each added to their version of the blockchain resulting in two parallel blockchains beginning to form.
  2. A stale block is a mined block that was mined correctly and added to a version of the Blockchain that as been dropped for another longer version of the Blockchain.
  3. A stale blocks occur when shorter version of the blockchain are dropped for validation of the longer version of the Blockchain at that time. Mined blocks from the shorter versions are called stalled blocks. If not mined yet, transactions from those block will be sent back to the mempool in order to get picked by miners once again.
  4. What requires, essentially, the physical data to be efficiently distributed is a 10 minutes delay between each block that is mined globally. If this delay becomes shorter over time, this might increase the chances of having several versions of the blockchain spreading on the network in a parallel manner until the longest version of the blockchain is chosen as the one valid version, leading all other versions to be dropped. This is resulting in Stale blocks to be rejected by the network and non-yet-mined-transactions to be returned to the mempool of pending transactions.
    Depending on the protocol, we generally consider that 6 confirmations (6 blocks mined after the block that contains your transaction in Bitcoin’s Blockchain) are secure to unsure your transactions are now added to the longest blockchain and, therefor, the only valid and immutable mined version of the blockchain.
#786

  1. What happens in the bitcoin network when two miners solve a block at the same time? The block with the longest version of the blockchain will be accepted and the other block will dropped and become a stale or orphaned block and those transactions go back to the mempool.

  2. What is a stale block? Blocks that were once in the blockchain but were dropped because there is another version of the blockchain that is longer.

  3. How do stale blocks occur? when two blocks of truth are be produced at same time and propagated through the network and one of those blocks are dropped because the blockchain chose the block with the longest version.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction? In the case of if your transactions in ends up in a block that becomes orphaned or stale. You should wait for 6 confirmations.

#787

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    Depending on which blockchain gets built on faster and becomes bigger then the other will determine which chain will stay. The dropped chain is also known as stale block or orphane block.

  2. What is a stale block?
    It is a block that has been overrun and dropped by the consensuce of the nods.

  3. How do stale blocks occur?
    When a block is simultaneously forged that are both confirmed but is dropped because there can not be two of the same transactions. So the one that gets confirmed is the chain who miners build on the most. The staleblock is the block that gets dropped.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Because you then know that your transaction is set in the blockchain and not dropped so wait until 6 blocks are built on the chain.

#788

  1. If two different blocks are mined at the same time, each would be propagated to and received by the nodes closest to the mined block. This would result in two seperate chains temporarily being broadcast over the network.

  2. A Stale (or Orphaned) block is a valid block that was mined within a shorter chain. If a longer chain is mined, all transactions in the block within the shorter chain would be sent back to the mempool.

  3. Stale blocks occur when a valid block is mined, but then a longer chain (or one with more POW) is created.

  4. It is important to wait longer than 1 block to confirm a transaction as, even though the block is valid, it may become a stale block and returned to the mempool, due to the fact that it is more likely to be within the longest chain in the network, therefore within the ‘true’ blockchain.

#789

1. What happens in the bitcoin network when two miners solve a block at the same time?
Both blocks are valid and the blockchain is split (forked). Some miners adopt one version of the chain (a), and some the other (b). The next block decides which version of the chain will win (the longest chain wins). If the miners on chain version a find the next block first then the blocks in version b will be dropped and the transactions in these blocks will return to the mempool.

2. What is a stale block?
A stale block is an abandoned block that was mined correctly but was on the shorter chain.

3. How do stale blocks occur?
Miners find the solution to an equal height block at exactly the same time, the chain is split and the block(s) on the shorter chain will become invalid.

4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
So you are absolutely sure that you’re transaction is not in a stale block stat will be dropped and your transaction invalidated.

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#790

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

  • chain forks
  1. What is a stale block?
  • block that was in the blockchain but then dropped because another block that was produced at the same time is part of the longer chain.
  1. How do stale blocks occur?
  • occur after a fork is resolved with a longer chain
  1. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
  • to ensure that the block your transactions are in and not dropped from the chain.
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#791

  1. they both will broadcast their block to the network and depending on how far they are from each other (geographically) some part of network may get one block first and the other can get the other one first. Both blocks are correct and valid (with correct nonce and valid transactions) so now for some time there are 2 versions of blockchain in circulation.
    Situation is solved by the next miner when next block is mined - it is appended to one version of two valid blockchains and this new longer blockchain now gets adopted by the whole network because longer blockchain is always the more important one.

  2. stale block is the dropped out block from the example above - was mined at the same time as the competing block on the other side of the network, was valid part of blockchain for some time but then was replaced by the longer blockchain and was dropped by the network. All transactions from that blocks were returned to mempool.

  3. are mined at the same time as block from different miner (as per 1) and 2) … )

  4. to make sure that the block with that paricular transaction will not turn out to be stale block in next several block times.

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#792
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    They create two competing chains
  2. What is a stale block?
    A stale block is a block that is dropped when there are 2 competing versions of the block chain.
  3. How do stale blocks occur?
    They occur when 2 miners mine a block 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 ensure that your transaction is not a competing chain and ends up being the stale block
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#793

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    If two miners solve a block at the same time then the blockchain will have 2 paths for both blocks until one path becomes longer than the other. The shorter path will be dropped.

  2. What is a stale block?
    A stale block is a block that was once confirmed and added to the blockchain but then dropped because another version of the blockchain supersedes it.

  3. How do stale blocks occur?
    Stale blocks occur when blocks are dropped from the blockchain because there is another version of the blockchain that has been accepted and trusted as the true blockchain.

  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 when sending or receiving a transaction because there is a chance that the block containing your transaction can be dropped from the blockchain and becoming a stale block.

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#794

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    Both of these blocks will be propagated to the network. the nodes across the network will have one version or the other of the truth. Another miner will solve the next block and append it to the blockchain. Depending on what version of the truth the winning miner was working off of will now become the longer chain and be recognized by all nodes as truth. The other loser block will then a stale or orphan block. The transactions the will be return to the mempool.

  2. What is a stale block?
    A stale block is the loser block in a situation when two miners solve the difficulty puzzle and begin to propagate a block onto the network at the same time. The block that is rejected as the longer chain is removed from the blockchain and the transactions return to mempool.

  3. How do stale blocks occur?
    When two competing miners solve the difficulty target at the same time and propagate their block across the network to other nodes
    See answers 1 and 2

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Because the transaction may be confirmed on a block that can potentially be orphaned. Your transaction could be returned to the mempool.

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#795

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    this makes 2 different chains (truths).

  2. What is a stale block?
    It’s a block that got dropped before it got 6 confirmations.

  3. How do stale blocks occur?
    The network always chooses the longest chain, therefore when two different truths exist - if your block is in the shorter chain, your block will be dropped and transactions goes back to mempool.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    To ensure the block has been propagated to the network.

#796

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    The chain forks until a new block is added to one of the 2 chains, then all transactions from the shorter chain are sent back to the mempool and the longest chain continues.

  2. What is a stale block?
    A stale or orphaned block is one which is valid but due to a fork in the chain is now not accepted because it is the shorter chain.

  3. How do stale blocks occur? Stale blocks occur when two valid blocks are mined at the same time, the next block to be mined and attached to the blockchain will determine which chain of the fork continues (the longer chain) and the block from the shorter chain will become ‘stale’ and dropped back to the mempool.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction? To ensure that the block which has the transaction does not become a stale block.

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#797
  1. What happens in the bitcoin network when two miners solve a block at the same time?

When two miners solve a block roughly simultaneously on the bitcoin network both blocks will temporarily become valid. Miners then have the option of including either hash in their next block. The next block to be mined will decide which block stays in the chain as the longer chain will always be selected by miners to build on top of. The other block will invalidated and have its transactions returned to the mempool.

  1. What is a stale block?

A stale block or orphaned block is the result of two blocks being mined at the same time. The block that becomes part of the shortest chain after further mining becomes a stale block.

  1. How do stale blocks occur?

Stale blocks occur when the two blocks are mined at the same time by different miners. Only one will be permanently appended to the blockchain and the other will become a stale block.

  1. 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 multiple confirmations after recieving a transaction because the first few blocks have a higher chance of becoming stale and rentering the mempool. This may result in the transaction becoming reversible for a period of time. After a few blocks have been mined it is safe to close the transaction since any competing blocks will have likely been discarded.

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#798
  1. What happens in the bitcoin network when two miners solve a block at the same time? - 2 different chains are created with 2 different versions of truth
  2. What is a stale block?These are dropped blocks
  3. How do stale blocks occur? Stale blocks result from two miners solving the block at the same time. The block that is not selected is dropped and all transactions go back to the mempool
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?You need to confirm your transaction is not dropped becoming a stale or orphaned block
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#799

Both block are valid but each of them is propagated to the closest nodes so at that point there are two versions of blockchain which are different only in the last block. The miner who will mine fastest the next block will append it to the one which he as a node had. The other block will be removed and became a stale block.

Stale block is block which was part of the blockchain and was removed because other miner mined new block and appended it to the longer chain. All transactions in a stale block are returned to the mempool.

When two miners solve the block at the same time with nonce lower that target and starts to propagate it to the closest nodes.

Because we want to make sure that the block, in which the transaction occurred, is not a stale block.

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#800

  1. You get two different blockchains. If on of these blockchains gets longer or rather get more proof of work it will be accepted by the network. The other one will be removed and all the transactions go back to the mempool.

  2. The block that get removed as mentioned in 1.

  3. If two miners solve two blocks at the same time. The block that get removed is the stale block

  4. To make sure your transactions isn’t included into the stale block that get removed

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#801
  1. What happens in the bitcoin network when two miners solve a block at the same time?
  • whichever one is longer after 6 confirmations longest chain is “correct”
  1. What is a stale block?
  • it used to be valid but got dropped, and it returned to the mempool
  1. How do stale blocks occur?
  • by another longer chain confirming blocks that the stale one used to be part of that are no longer needed because they are part of a shorter chain than the one replacing it.
  1. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
  • To make sure that the transaction you are sending or receiving will be a valid block and not orphaned after 2 confirmations etc.