Homework on Stale Blocks

Blockchain and Bitcoin 101
#2069

Yes, I have revised it to read …

More blocks added to the chain after the block containing your transaction (more than 1 confirmation) is required to ensure that the block …

#2070

they both go on the blockchain until the next block comes along and chooses which one to go on top of and at that point the other block becomes a stale block & the transactions in the block go back to the mem pool because their is now a longer chain that everyone else will follow

a stale block means that it’s transactions are no longer part of the blockchain and they go back to mem pool

a stale block occurs because two blocks at the same time were propagating the blockchain at the same time and the next block chose the other block instead of this one that is now a stale block

this allows enough time for all the nodes to make sure they have the correct blocks in the chain so as not to have different blocks

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#2071

  1. The blockchain splits into 2 valid blockchains.

  2. A stale block is a block which was dropped by the network, because it was no more part of the longest valid blockchain.

  3. Stale blocks occur when, for a certain period of time, several blockchains appeared as valid and then, finally, one of them grew quicker than the other ones, hence becoming the longest blockchain toward which the network switched automatically (as nodes are programmed to always take the longest blockchain). All the child blocks not part of this longest blockchain becomes obsolete (stale).

  4. Waiting for 6 confirmation blocks is recommended in order to ensure one transaction is not part of a block which becomes stale because of a fork.

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#2072

  1. When two miners solve a block at the same time, the blockchain forks into two chains, there are now two versions of the truth, but can be different because the transactions in each block can be different. Basically there are now 2 versions of the blockchain being propagated to the nodes in the bitcoin blockchain network.

  2. A stale block is a block that was in the blockchain but was dropped as there was a longer version of the blockchain without those blocks in it.

  3. Stale blocks occur when 2 miners successfully add a block to the blockchain at the same time. Once these blocks are added to the blockchain there are now two versions of the blockchain in existence. The two versions of the blockchain are now added to the network and begin being propagated to the nodes in the network. When a miner picks up one of these versions of the blockchain and successfully mines a new block it is added to the version of the blockchain he found on the network. Once he successfully adds his block to the network, his version of the blockchain is longer than the other version of the blockchain that was on the network at the same time. The longer version of the blockchain becomes the “truth” and the block that was successfully mined the other miner becomes a stale block as it is not part of the newly created longer blockchain.

  4. It is important to wait so that the transaction can be propagated throughout the whole network.

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#2073

They are both accepted by the other nodes who hear it first. Miners will always work on the chain with the most PoW. If identical they just work on the one they heard of first.

A block that got pruned from the chain because it ended up being in a competing side-chain that did not have the most PoW.

Two blocks of equal PoW get mined the same time. Both is continued by some miners. The stale side-chain of blocks will be the one that ends up having less PoW. Txn’s unique to the stale blocks get put back in the mempool.

Your transaction might have been mined into a stale block. The probability of being in scale block drops off (I guess exponentially) with each successive block after your own.

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#2074
  1. You could end up with a situation where part of the network has added one new block to the chain while another part of the network has added a different block to the chain.
  2. A stale block is the block that gets dropped from the chain, and all the transactions contained in that block return to the mempool.
  3. A stale block occurs when another miner appends a new block to one of the competing blocks mentioned in the answer to question 1. The one that is not selected by the miner to build the new block becomes a stale block.
  4. If your transaction ended up in the stale block, that transaction goes back into the mempool. You wouldn’t want to assume the transaction took place because if goods/services were to change hands, what would happen if the transaction never happens? Someone does not get paid in that situation, so obviously that needs to be avoided for a variety of reasons but ultimately, it would erode trust in the reliability of the entire system.
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#2075
  1. There are then two valid blocks that are propagating through the network.
  2. A stale block was once a part of the blockchain, but got dropped. The transactions that were in the dropped block go back to the mempool.
  3. When there are two valid blocks at the same time, the next block will be linked to one of the two blocks. The block that gets picked by a miner lives on as part of the blockchain. The other becomes a stale block.
  4. Waiting for more than one block to be confirmed reduces or totally removes the risk of a confirmed transaction being returned to the mempool.
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#2076

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    when two miners produce a valid block at the same time, whatever block the miner of the next block chooses to append it too will be the longest chain, and the other block with be dropped, returning all of its transactions to the mempool.

  2. What is a stale block?
    A stale block is the block that gets dropped and returns its transactions to the mempool as described in my answer above.

  3. How do stale blocks occur?
    I think I explained this in my first answer.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?It is best practice to wait until your transaction is 6 blocks deep to consider it confirmed because of the possibility of stale blocks dropping your transaction and returning it to the mempool.

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#2077
  • What happens in the bitcoin network when two miners solve a block at the same time?
    They both propagate to the other nodes, eventually one will win (with the ‘longest chain’ f(length, difficulty)) the other block will go stale.
  • What is a stale block?
    block that was mined, but was not included in the blockchain
  • How do stale blocks occur?
    a different block from different miner was added to the chain, and won the longest chain contest
  • Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    the block that your transaction is in may not be added to the blockchain, so your transaction will have to be mined again
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#2078
  1. You have to wait until the next block is propagated order to see which of the 2 blocks will be accepted into the blockchain, and the orphan block transactions will be out back into the mempool.
  2. Stale, or orphan blocks have another version of truth, but the next miner chose the other block as the block to build upon and stated in answer 1
  3. Stale block occur when 2 miners validate 2 blocks at the same time.
    4 To see which path is chosen and your transaction is not reverted back into the mempool
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#2079
  1. The chain forks temporarily (this is usually resolved in the next block or two.
  2. A block that gets put back into mempool in favor of chain with more POW (longer chains survive and the other block is returned to mempool.
  3. Stale blocks occur after a fork is resolved with a longer chain the stale block is the one returned to the mempool
  4. In case of a stale block occurring. Best practice says 6 confirmations.
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#2080
  1. Both the blocks will propagate through the nodes, but eventually one of them will be picked up the next miner and that block will be considered as valid and hence the other block will be dropped.
  2. Stale block is a previously valid block but was dropped because it wasn’t part of the longer blockchain.
  3. Stale blocks occur when more than one blocks are mined at the same time. Only one of the block will be added to the blockchain and the remaining blocks are dropped and their transactions are send to the mempool.
  4. This is because a confirmation on a single block can be dropped as it may turn out to be a stale block or even a rouge block, hence it is essential to wait for more confirmations.
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#2081

  1. there is no draws there is only 1 winner so longest chain wins.

  2. a stale block is a block that was rejected by the network which is moved to the mempool

  3. when 2 miners mine a block ay the same time.

  4. it will ensure that the block containing your data isnt dropped from the blockchain

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#2082

  1. One of the miners will eventually become a stale block as the opposing miner will link to the longest chain.

  2. A stale block is a block the was in the blockchain but then dropped/invalidated.

  3. Stale block occur when a miner creates a block that is not validated and gets returned to the mempool.

  4. it is important to wait for at least 6 confirmation as rule-of-thumb to make sure your block isnt dropped.

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#2083

1 - The block is accepted and begins to spread through the different nodes, therefore there are two fully valid versions of the blockchain, but only the longest chain with greater difficulty will be accepted.

2 - The block that is taken from the chain, despite being totally valid, is what is called a stolen block or an orphan block. Your transactions are returned to the mempool

3- Since we do not know if our transaction is not in a block that may be one of the orphans. That is why it is recommended to wait 10 min or 6 block confirmations to make sure that our transaction is on the Blockchain

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#2084

1.- When two miners solve a valid block at the same time, each new block is announced to the nodes near the miner and for a moment there is two versions of the blockchain. The situation gets resolved once the next miner append the next block. Since the network will always accept the longest chain the version of the blockchain that got extended first becomes the accepted blockchain and the other block gets orphaned or staled. The transactions in the orphaned/staled block return to the mempool.

2.- A stale block is a valid block that got dropped-off the network because the blockchain continued on another block.

3.- As described in point one, a stale block occurs when two or more blocks are created at the same time, but one gets accepted by being appended with a new block faster than the other one.

4.- Sometimes your transaction could have been added to a block that gets staled or orphaned. It is generally accepted that after 6 confirmations your transaction has been fully accepted and recognized in the blockchain.

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#2085

uncle-block
uncle-block784×154 5.52 KB

1-the next block continues to mine one of them and the next in the chain of blocks with more pow, the information contained in the obsolete block goes back to the mempool
2-is a block that becomes obsolete and returns to the mempool
3- occur when solving the problem at the same time and thus a temporary fork occurs until it is resolved with a longer chain
4- to avoid obsolete blocks

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#2086
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    In this scenario the blockchain essentially creates a fork as the 2 miners pass their block as valid and correct for authentication onto other nodes. Now there are 2 different valid blockchains on the network. This could happen multiple times on each fork of the blockchain as it passes out throughout the network, until one of the nodes receives both versions the forked blockchain to authenticate.

At which point, the fork with the most completed blocks remains as the blockchain and the other blocks on the other chain are dropped from the chain because they are not in it and sent back to the mempool.

  1. What is a stale block?
    A stale block is the name given to a block that is dropped in the process above. A stale block can also be referred to as an orphan block.

  2. How do stale blocks occur?
    By 2 miners completing a block at the same time and 2 versions of the blockchain are present on the network

  3. 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 6 confirmations of completed blocks to ensure that the block is not dropped from the chain.

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#2087
  1. Assuming these blocks were verified as the truth by consensus then the two blocks will start to propagate to other nodes, starting from those nearby to the miners. This leads to a situation where two separate verified versions of the blockchain exist at the same time.

Example: One version of the blockchain will have the verified Block X (Not Y) while the other has Block Y (Not X). Assuming both of these blocks were mined at the same time.

New miners joining the network at the time will also have one of the two versions of the blockchain and so they will mine according to this information. If more blocks become mined on one of these versions by the new miners then the version with the longest chain will continue existing and propagate to the entire network.

Meanwhile the blockchain with the shortest chain will be discarded by the network and so the version of this block will be dropped along with its transactions. Those transactions will then go back to the mempool to be re-mined.

  1. A block that was verified as part of the blockchain but was later excluded as it was no longer part of the longest chain.

  2. They occur when two blocks are mined at the very same time causing two different versions of the blockchain to appear on different nodes with either of those blocks existing. This eventually leads to one of these blockchains to become invalid (due to longest chain) and so the block part of the invalid blockchain becomes stale.

  3. Because there’s a chance the transaction may have to be re-mined should it be invalidated if the block it was initially mined to became stale.

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#2088

  1. They both get accepted by different nodes creating two temporarily valid blockchains.

  2. When two blockchains are valid, eventually one will become invalid as future blocks are mined and one will become a stale block.

  3. When two blockchains are valid because two miners solved a block at the same time, the future block will linked to only one of those valid blocks thus creating a longer blockchain. Once a blockchain becomes longer than the other, the shorter blockchain will become invalid and all transactions on that blockchain will be returned to the mempool.

  4. If there are less than a few confirmations for your transaction, their is a possibility that your transaction could be on a block that will eventually become a stale block.

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