Homework on Stale Blocks

Blockchain and Bitcoin 101
#341
  • What happens in the bitcoin network when two miners solve a block at the same time?

Both blocks will be added to the blockchain of the nearest situated nodes. But at the same time, different blocks are propagated through the network.

That means that in the world there are two versions of the blockchain circulating at the same time.

In consequence, the next block to be mined will be added to one of these previous blocks, depending on the version of the blockchain they work with and finally the network will continue to mine on the longest version of the blockchain.

  • What is a stale block?

A stale block is a valid block that drops from the blockchain, because it hasn’t got enough validations and the network chooses always the longest chain to mine on.

  • How do stale blocks occur?

Stale blocks occur when at the same time 2 or more different and valid blocks are propagated through the network. That means that in the world there are two versions of the blockchain circulating at the same time.

In consequence, the next block to be mined will be added to one of these previous blocks, depending on the version of the blockchain they work with and finally the network will continue to mine on the longest version of the blockchain. The longest version of the version will be accepted as the greatest version of truth.

The blocks that will not be mined on anymore will drop from the blockchain, and return to the mempool.

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

It’s always better to wait for 6 confirmations. That means that 6 other blocks are mined after the block that contains your transaction. This is because the network will always choose to work with the network that has the longest chain to continue adding blocks too.

In that case you are sure your transaction is confirmed by the network, and will be immutable.

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#342
  1. When two miners solve a block at the same time, each of their block version will be sent to the closest nodes in the network. There will be two versions of the blockchain.
  2. A stale block is a block that was in the blockchain during a short period of time then got rejected.
  3. Stale blocks occur when it is no longer part of the longest blockchain version. The longest block line always wines since the PoW is higher than the other block lines. Once a block becomes a stale / orphaned block, it drops from the blockchain and is put back to the mempool waiting to be confirmed once again.
  4. The goal of transaction confirmation is to have the longest version of truth. The more blocks will be confirmed the more likely my transaction will be too. The odds for the block containing my transaction of being stale will be very low.
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#343

1. What happens in the bitcoin network when two miners solve a block at the same time?
The network will choose the block which in the longer blockchain, and the block which in the shorter blockchain will be dropped and added into the mempool.

2. What is a stale block?
Stable block that means some block have been added into the blockchain, but later were dropped into the mempool because of the competition of miners.

3. How do stale blocks occur?
I think it is the same question, the answer please look at the 2 question.
4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
Because if one block is confirmed, that means after this block, there are six confirmed blockchain. The case of stable block will be decreased, and the network will be more effective.

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#344
  • 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 both blocks are added to the chain and get passed to nodes. The next block is mined on top of one of the two blocks in question, nodes will always recognized the longest chain as the correct one.

  • What is a stale block?

*A stale block is the block that has been solved however the rest of the network placed it aside because some other miner got their block verified by someone else faster.

  • How do stale blocks occur?

Stale blocks occurs after a block is successfully solved but before it is verified by the rest of the network.

  • 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 just in case your transaction happened to be on a set of stale blocks.

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#345

  1. it temporarily splits the blockchain untill the true block wins

  2. the block that does not prove to be true and gets dropped back to the mempool

  3. when miners solve a block at the same time it creates another block simultaneously, one of wich will be come invalid or stale

  4. to make sure your transaction has successfully made it onto the true blockchain

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#346

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    They add their block to the blockchain, so now we can have 2 versions of blockchain propagating on network. However as soon as a new miner selects one of these chains and adds a new block, we have one blockchain longer than the other. The longest blockchain takes precedence the shorter blockchain is dropped.

  2. What is a stale block?
    A confirmed block and up to 5 additional blocks can be dropped from a version of the blockchain if a longer blockchain exists. The dropped blocks are known as stale blocks.

  3. How do stale blocks occur?
    When a block is confirmed into the blockchain but then its blockchain superseded by a longer blockchain the block that was just confirmed ( in the shorter chain ) is dropped, and known as a stale or orphaned block.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    By waiting for 6 blocks the blockchain can ensure only 1 version of the blockchain is propagated and other “competing” blockchain dropped.

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#347
  1. Then two blocks are formed on the block chain until one of them produces a longer chain because more blocks are validated in that chain then the shorter chain is rejected and the other block is deemed a stale block or orphan block and is rejected.
  2. A stale block is one that has not had enough blocks added to it in time and has been rejected by the network.
  3. Stale blocks occur when two blocks are validated at the same time and one of them block (A) has a longer chain of blocks added to it and is validated sooner than the block (B) which is rejected by the network and becomes a stale block.
  4. The general rule is to wait for at least 6 blocks to be confirmed so that the chain you are on is not rejected and your transaction becomes part of a stale block. Then all the transactions are returned to the mempool.
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#348

1] Stale blocks are those that have been dropped in favour of a longer blockchain. All the UTXo’s are returned to the mempool

2] Due to network latency it is possible where two separate blocks are being mined concurrently

3] The blocktime 10 minute rule minimises stale blocks in the network

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#349

1-3) At some point a third miner will also mine a block and add it to one of the two blocks that were mined simultaneously. The network of miners will then choose the longer of the two chains. The block that was left out will be a stale block or orphan block and will return to the mempool
4) The block times are kept at approximately 10 minutes to give enough time for the new block to be sent to all the miners and nodes on the network and to be accepted as the true blockchain

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#350
  1. It will split
  2. Stale block is the dropped block which is sent back to mempool.
  3. After network is split into two versions (A, B), then some miners will pick the closet version (A) then this one will be the longest blockchain and all nodes will agree where the other version (B) will be stale.
  4. To confirm the longest chain accepted by the network
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#351
  1. There are two valid blockchains for a time.
  2. A block on a blockchain that wasn’t included in the current longest blockchain (with most hash power used).
  3. Because your transaction may be in a stale block and not included on the future version of the accepted blockchain.
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#352

  1. Both are legitimate blocks and, initially, both are propagated.

  2. A stale block is a legitimate block that was not added to the main chain. That is to say, there was a small unintentional fork that was later resolved against the favor of the stale block. This stale block is no longer considered the “truth” of the network.

  3. Separate miners incidentally mine a block at the same time creating a fork. One fork is added to next, making it the main chain, while the other block is said to orphaned or stale

  4. A txn could accidentally be included in a stale block which could be invalidated, or at least un-confirmed, when the blockchain reconsolidates against the favor of the txn.

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#353

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    The blockchain forks until a consensus is reached to determine the valid block. The stale block transactions are put back into the mempool until a new block collects them.

  2. What is a stale block?
    A block that had to be removed to prevent the chain from forking because it was discovered by two miners simultaneously.

  3. How do stale blocks occur?
    If 2+ miners discover the nonce at the same time and produce a block, the chain will fork. After a consensus is reached, the strongest/longest block(s) remain on the chain and the forked blocks have their Tx’s sent back into the mempool. The latter are stale blocks.

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    To reduce the risk of using a stale block and invalidating the Transaction’s in it.

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#354
  1. When two miners solve a block at the same time they both get temporarily accepted to the blockchain. The one with the longer chain gets “officially” accepted while the shorter chained block gets discarded and transaction go back into the mempool.
  2. A stale block is the block with the shortest chain (that gets dropped) from a temporary fork.
  3. They occur when two miners mine a block at approximately the same time.
  4. You should wait for 6 blocks to be confirmed when sending or receiving a transaction in the case a stale block exists.
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#355
  1. The 2 blocks are propagated through the network and the network has 2 version of truth till the next block arrive.
  2. Stale block is the block drop off after the network choose the longest version of the chain.
  3. Stale blocks occur when there is 2 blocks came out at the same time and the network choose 1, then the other one is called stalled or orphan.
  4. Because that one block can be the Stale block and can be droped by the network.
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#356

  1. one of them becomes a orphan / stale block

  2. a stale block is a valid block with a valid nonce but with a lower PoW than an other valid block which will get the block rewards. the stale block will be deleted and the “better block” will become a part of the blockchain. all transactions from the stale block will go back in to the mempool.

  3. a still block occurs when 2 or more miners produce a block at the same time.

  4. your transaction might be confirmed by a stale block in which case your transaction, which was previously confirmed goes back in to the mempool and the stale block gets dropped. 6 blocks after your confirmation you can be sure that your transaction is in the blockchain for good.

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#357

  1. Sooner or later, there is a new miner who solves the next nonce and this one will chose the longest chain of the 2 solved at the same time to use as input for the next block. The orphaned block will be rejected and those tx’s will go back into the mempool to wait to get picked up by another miner.

  2. A stale or orphaned block has been dropped by the network because it did not have the longest chain.

  3. When 2 miners solve a nonce at exactly the same time.

  4. More than one block confirmation (best practise is 6 conf.) means that the odds are reduced that your tx has not been dropped in a stale block because the network is actually propagating it.

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#358

1- The two blocks are propagated through the nodes that are closer to the miners who solved it, and this happens at the same time, so two versions of truth form.

2- Is a block that ends up being ignored by the network because another block that was solved at the same time got more confirmations and formed a longer chain of blocks in a 10 mins period

3- Two miners solved a block at the same time and one of them has to be accepted so there is no bifurcation in the blockchain, so the rejected one is the stale block.

4- Because that way we know our transaction is not going to end up in an orphan block.

#359

  1. It will result in a split of the blockchain until one of the chains grows longer than the other. The longest chain is then used by the entire network.

  2. A stale block is a valid block dropped from the blockchain.

  3. The same blocknumber is mined twice at exactly the same time and propagated to the network. The two blocks exist simultaneous and new blocks can be added to the chains until one chain becomes longer than the other. The longer chain is accepted, the blocks in the shorter chain are dropped.

  4. Your transaction could be in a stale block. If you wait 6 confirmations you can be sure your transaction is in a block that is accepted by the entire network.

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#360
  1. What happens in the bitcoin network when two miners solve a block at the same time?

Two versions of truth exist (2 blockchains). The one which is longer is accepted by the network. It depends which blockchain gets appended the next block. Or one more than the competing blockchain.

  1. What is a stale block?

It is a block that was created my the miner of which blockchain was shorter than the competing one. All the Tx from that block goes back to the mempool.

  1. How do stale blocks occur?

When 2 miners or more solve the puzzle (find the suitable nonce) in the same time, two/more versions of blockchain exist in the same time in the network. Stale block is a block that was appended on the blockchain that was not accepted in the end.

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

Because in that way we can reduce the possibility for transaction to be put back to the mempool. If so the transaction is still unconfirmed.

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