Homework on Stale Blocks

Blockchain and Bitcoin 101
#1807

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    There will be two versions of the same block flowing across the network, i.e. different versions of truth. The one which is able to get blocks appended to it quicker will become the best blockchain.

  2. What is a stale block?
    Stale Blocks are blocks that are dropped from the current blockchain because they were overridden by a longer chain.

  3. How do stale blocks occur?
    More than one block were successfully mined block succesfully mined at the same time, and the one which is able to get blocks appended to it the fastest will become the best blockchain. Others will be dropped and become stale block.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    It is because the block containing the current transaction may be dropped and become stable block because there is another block becomes the best blockchain.

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#1808

Yes, but keep in mind that this block is mined at the same blockheight than the other block and that these blocks are not identical. (so the nonce and blockhash will be different)
Each block will probably have different transactions init. Miners create a candidate block and pick transactions from their own mempool. Depending of your location, your mempool can have transactions that other nodes don’t yet have (because it takes time to propagate) but usually, miners pick transactions with the highest fee first, so in most cases, both blocks will have lots of transactions that are included in both blocks.

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#1809

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    both will be added to the bitcoin network. The one with longest (in terms of difficulity) will be adpoted eventually, and the shorter one will be come a stale or orphaned block

  2. What is a stale block?
    Stale block is a block dropped by the network when a competing block is adopted as the official block due to its longer block size.

  3. How do stale blocks occur?
    Stale block occur when you have two or more competing blocked added (forked) in the network. Eventually a block with longer and more difficult history will be adopted, leaving the remainder of blocks as stale blocks.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    to make sure the block you are working on is the official adopted block, and not a stale block.

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#1810

  1. When two miners solve a block at the same time it momentarily creates two versions of the truth on the network, but only until the next block is solved and upended onto the chain.

  2. A stale block is the block that gets dropped when two miners produce a valid block at the same time.

  3. A stale block occurs when two miners produce a block at the same time; one block will be continued and the other will be dropped. The dropped block is called a stale block.

  4. It is important to wait for more than one confirmation because your transaction may be in a block that will be dropped; A good rule of thumb is to wait 6 confirmations to know for sure that your transaction made it through.

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#1811
  1. What happens in the bitcoin network when two miners solve a block at the same time?

Both blocks are added to the blockchain as they are both valid. They propagate via their nearest nodes.

  1. What is a stale block?

A stale block is one that has existed on the blockchain, but has since been dropped by the network.

  1. How do stale blocks occur?

Stale blocks occur where 2 miners produce 2 different valid blocks at the same time. The following block that is added to the blockchain will follow on from only 1 of these blocks. The block that has not been followed by the latest block is thus dropped from the network, as the other chain is now the longest.

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

Best practice is to wait for 6 block confirmations as the transactions in a block may be dropped.

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#1812

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    A: When two miners solve the cryptographic puzzle at the same time they will each send their block out to the network, i.e. nodes of the world. The miner who gets added to the block chain is dependent on how many nodes of the network pick up each individual block/hash faster, and depending on whose block gets added to first, thus becoming longer. The longer chain will be added to the blockchain, the other block will become dropped.

  2. What is a stale block?
    A: A stale block is a block that was created at the same time as another but lost the “race” to have more blocks added to it, and hence is dropped from the chain.

  3. How do Stale blocks occur?
    A: Stale blocks occur when a miner’s block is dropped from the blockchain. This is due to the miner’s block being created at the same time as another miner’s block, and said block is added to first and more, creating a longer block.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    A: It is important to wait for more than one block to be confirmed (best practice is waiting for 6) when sending or receiving a transaction because in case of two miners creating a block at the same time, the block with your transaction could be dropped.

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#1813

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    Both new blocks will be propagated to different nodes all over the network. Whichever block gets connected to a new block the fastest will then become part of the legitimate blockchain. This is because the network accepts only the longest chain as the ONE legitimate blockchain.

  2. What is a stale block?
    A stale block is when a solved block is dropped from the network. A solved block is dropped from the network if it fails to be extended to be the longest block on the network by subsequent miners.

  3. How do stale blocks occur?
    It occurs when there are multiple solved blocks are generated at the same time. But because only one of them could eventually win, the one that does not get extended into new blocks first gets dropped. And when that block gets dropped, it is considered to be a stale block.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Because you never know if the block is going to be dropped or not. It is advised to wait until 6 confirmations in order to have enough time to determine which block needs to be dropped or validated. Usually there will be “2 versions of the truth” at first, but after a few extensions of the blockchain, there will only be 1 version of the truth.

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#1814

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

  2. What is a stale block?

  3. How do stale blocks occur?

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

  5. the longest blockchain will win and the other block will be a stale block also called orphaned block. 2. stale block also called orphaned block was the block that was produced at same time but was on shorter chain so it lost.
    3.when to miners mine a valid block at the same time

  6. transaction could be orphaned if it doesn’t have enough confirmations to secure the blockchain (6 confirmations now)

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#1815

  1. If two miners each mined a valid block at the same time there would be two versions of the blockchain on the network both are valid. Each miner will propagate their version to nearby nodes. Since the network will only accept the longest chain with the most POW done whichever version add the next block to their chain first become the longest chain and the other version dropped.

  2. A stale block is a valid block that becomes a part of the blockchain and then dropped. It’s no longer valid. All transactions in the block return to Mempool to be confirmed.

  3. When there are two versions of the blockchain competing to be the longest chain. Discarded blocks become stale blocks.

  4. To make sure that your transaction will not reverse if a stale block occurs.

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#1816
  1. They both get propagaded in the network and the one that has another block attached to if first will be the accepted one and the other gets dropped.

2.its a valid block that gets dropped because another valid block already had another valid block added to it which created a longer blockchain and the longer block chain is the one that always wins.

  1. They occur when 2 miners create a block at the same time. They both get propagaded but the one that gets another new block attached gets kept and the one that didnt is called a stale block or orphaned block.

4.because the block with your transaction might get dropped. If you wait for 6, youre safe

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#1817

1The block with the longest chain wins
2 Stale blocks are the transactions that didn’t’ get added to the chain because they were not confirmed by the longest chain
3. It comes from the partially confirmed block that was not part of the longest chain. The unconfirmed trx get put back into the mempool and will wait to the next block to get added to the blockchain
4: The node that confirmed the transaction may not be the final block that is added to the chain. One needs to wait until the block is added to the chain before being certain the confirmation was valid and approved by the nodes.

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#1818

  1. If two blocks are solved at the same time, the blocks that came later will eventually create the longest chain fastest. Since the longest blockchain prevails, the chain with the shortest chain of blocks will be dropped.

  2. Stales blocks are blocks that were dropped because they were part of a shorter chain.

  3. If two blocks are mined at the same time, the blocks coming after each fork will eventually create one fork longer than the other. At this point, the shortest chain is dropped. The blocks that are no longer p[art of the blockchain are stales blocks.

  4. While mining new blocks it is possible to have a shorter chain being dropped and with it all the new blocks. As the new blocks are no part of the latest valid chain, the transactions on the dropped blocks need to the mined again into new blocks. Therefore it is best to wait for six new blocks after our transactions to make sure our transaction is definitely part of the latest blockchain.

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#1819
  1. The blocks are appended to the blockchain regardless and different miners will select alternate versions and continue to compete. In this case the miner that solves the target fastest will propagate their blocks to the blockchain and the miner that solved the target slower, his / her blocks will be returned to the mempool and ultimately be discarded as the network will always accept the longest blockchain.
  2. A stale block is a block that has been returned to the mempool to be discarded as a subsequent longer blockchain has accepted by the network prior.
  3. Stale blocks occurs when one or more competing miners provide a longer blockchain to the network as the network will always accept the blockchain with the most PoW.
  4. The more confirmations the more secure the network preventing double spend (e.g. Finney attack where miner sends some coins back to his address without broadcasting the tx).
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#1820

  1. When 2 miners solve the puzzle at the same time, they start to propagate their block to the network. The closest nodes accept and append the closest miners block to their blockchain. They start to work on the next block immediately and append their block to their blockchain. In some time one chain gets longer than the other and the shortest one is disregarded from the blockchain.

  2. Stale block is a valid block which was once accepted and appended to the blockchain but later disregarded, because there was another chain getting longer.

  3. Stale blocks occur when there exist 2 blocks at the same hight. They are both valid, but one will be disregarded after some time.

  4. Because there could exist 2 chains in the blockchain for some time, but after some blocks one of the chains will be disregarded. Your transaction could be in that stale block so if you sell something and do not wait for the transaction to be confirmed, you could lose your money.

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#1821

  1. There will be two different block versions in existence until future blocks decide which version to attach to in which the other block is removed.

  2. Stale block are blocks which are dropped as they are shorter than the other chain (no longer appended to by new blocks).

  3. When two miners solve the nonce at the same time both versions are attached to the blockchain.

  4. To ensure the block is no later removed due to it being a stale block. Protection against a transaction being reversed or invalidated.

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#1822

  1. In a loggerhead situation, the block chain will be depended on the subsequent miner, which way does his node chooses to link up with, will determine the winner.

  2. A block that is no longer able to propagate further.

  3. When 2 miners are competing for a chain, the loser’s block which will be dropped is called stale block.

  4. This is to reduce the chance of being included in the stale block.

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#1823

  • What happens in the bitcoin network when two miners solve a block at the same time?
    Ans: Both the blocks are valid blocks and have the potential to get appended to the blockchain.

  • What is a stale block?
    Ans: A stale block is a valid block which got dropped because of competing blocks that get appended to the blockchain before the stale block is appended.

  • How do stale blocks occur?
    Ans: They occur because there are other multiple blocks which are confirmed/valid and the protocol is that the network/blockchain will accept new blocks which are longer in length compared to just one block (which will soon become our stale block).

  • Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Ans: So that we can avoid the situation of a block becoming a stale block.

#1824

But keep in mind that these 2 competing blocks probably doesn’t have the same nonce, because it’s impossible that their block is 100% identical. Each node picks transactions from their own mempool. Probably a different timestamp, and the coinbase transaction is to their own addresses, so the blockhash cannot be the same. But there can always be a chance that the nonce is the same, but defenitly not the entire blockhash.

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#1825

If 2 miners successfully mine a block at the same blockheight, they both can be propagated to the entire network if the next block takes time. Because of the rule of the longest chain wins (with most POW) it depends on wich of these 2 versions the next miner chooses to mine. Wich makes 1 blockchain longer than the other one.

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#1826

They are both appended to the blockchain, so this creates an accidental fork. So at this point, we have 2 valid blockchains with a different last block. Then it depends on wich of these 2 blockchains the next miner mines a new block on top of it. This makes 1 blockchain longer than the other one. And only then will that block on the shorter blockchain become a stale block

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