Homework on Stale Blocks

Blockchain and Bitcoin 101
#3591

  1. In this case the longest chain wins and the other block is said to be orphaned or stale. The transactions are returned to the mempool.

  2. A stale block is one that was in the blockchain but was orphaned because it was in a shorter chain.

  3. Stale blocks occur when there is a fork in the network due to two miners solving the problem at the same time.

  4. Because it is better to wait for six new blocks to insure confirmed transactions.

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#3592
  1. Two different versions of the blockchain will be propagate until the next block will be add to one of those and that chain will be the longer. the transaction of the rejected block will go in the mempool.
  2. Is a block that was in the block chain but dropped in favour a longer chain.
  3. the stale block occur when two miners mine a block at the same time
  4. To avoid a case of stale block.
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#3593

  1. Multiple versions of blockchain exist simultaneously. Which of these wins depends on which happens to get mined on first. When confronted with multiple versions of the blockchain, nodes treat the longest chain (the one with the most proof of work) as the truth and discard the alternatives.

  2. A stale block is a block which is discarded on account of not being in the longest chain.

  3. See answer to question 1.

  4. The longer one waits to treat a transaction as confirmed, the lower the likelihood of said transaction being in a stale block. Standard practice is to wait for 6 confirmations.

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#3594

  1. If two blocks are solved at the same time, both blocks propagate throughout the network. Both blocks “compete” to get linked to the previous block. Eventually, a third block will link to either one of the competing blocks and that will decide which block remains in the blockchain and the other block gets dropped.

  2. A stale block is a block that has been in the blockchain before, but it got dropped because there was another version of the blockchain that was longer without that block in it.

  3. Stale blocks occur when there are two blocks competing in the network to propagate and link to the blockchain. There can only be one version of the blockchain and the block that creates the longer version of the blockchain remains in it and the other block becomes a stale block.

  4. It is important to wait for 6 blocks to be confirmed before sending/receiving a transaction because a block can get dropped if the network finds a longer version of the blockchain.

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#3595

  1. The network splits into two. The one with the most PoW will win and the shorter one will be orphaned.

  2. Blocks that were dropped from the blockchain because there was another longer version of the blockchain.

  3. When two miners mine a block at the same time there will be two blockchains, the one with more PoW will win and the shorter one will be dropped and become a stale block.

  4. It is good to wait to see if a block has been orphaned.

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#3596
  1. What happens in the bitcoin network when two miners solve a block at the same time?

They wait to the network to confirm the valid one when propagating the next valid block

  1. What is a stale block?

A valid block dropped because the blockchain continues in a longer chain propagated by the network

  1. How do stale blocks occur?

When miners get a valid block and they spread the blockchain, could happen that 2 miners do it at the same time, the network keeps working to be validated 6 times

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

To know that the block is not dropped by the network

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#3597

  1. When two miners solve a block at the same time, both versions of the new block are propagated through the network, but one of them will eventually be discarded because the other will proceed to get another block appended and become part of the “longest chain.”

  2. A stale block is a block that is dropped as a result of another legitimate chain becoming longer.

  3. Two miners that successfully mine the same block number can’t both win. Eventually, only one of the blocks will win out and be part of the longest chain getting shared by the network. The block on the shorter chain becomes stale, and any transactions not in the winning chain are returned to the mempool.

  4. When you make a transaction, you can’t be sure that it isn’t in a future stale block unless you wait for several more blocks to be added onto the chain.

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#3598
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    One group of nodes will carry around a blockchain with one block at the end and another group of nodes will carry around a blockchain with another block at the end.
  2. What is a stale block?
    A Stale block is a block that was on the blockchain at some point but was later dropped for a longer blockchain with more proof of work. Dropped meaning they were not confirmed transactions they were sent back to the mempool where they wait to be confirmed.
  3. How do stale blocks occur?
    When a two miners miner A and miner B, for example, create blocks at the same time and another miner C - adds a block to miner A’s BC , miner B’s chain is dropped causing B’s blocks to become orphaned or stale blocks.
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Because the block that contains the transaction may get dropped from the chain and all data in it becomes invalid. The best practice is to wait for 6 confirmations, to make sure that the transaction was valid.
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#3599

  1. Validators closest to each of the miners will start validating two different versions of a new block onto the network. At that moment in time there will exist two different versions of the blockchain, one containing the block of miner 1 and another version containing the block of miner 2. Now the miners have to wait to see who gets the next block appended to their block because this will be the winner and become the ongoing version of the network. The block of the other miner will be rejected and all transactions in that block will be cancelled and put back in the mempool.

  2. A stale block is a block that is rejected from the network after it originally had been appended to the network because it was part of the shortest chain of two competing chains.

  3. See answer 1

  4. Once the next block has been created and appended to the blockchain, in case of two previous blocks being mined at the same time the, your transaction has either been validated and accepted by the netowork or rejected because it was part of the stale block. Either way frm that point on you have certainty about the validity of your transaction because as we learned previoulsy appended blocks on the blockchain are immutable.

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#3600
  1. When two miners solve a block on at the same time there is a divergence in the blockchain. The one that ‘wins’ and remains a part of the blockchain is the one that solves blocks fastest. The orphan chain then falls off, and the contents (txs) are sent to the mempool.
  2. Stale blocks are those blocks that were part of the blockchain at one time but are not any longer.
  3. Divergence in the blockchain when miners create new blocks at the same time. The chain that is able to solve succeeding blocks faster and create the longer chain wins out.
  4. it is important to wait 6 blocks for a tx to go through because it is highly unlikely at that point the tx you sent was in a stale block, and one could be very certain their tx went through.
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#3601
  1. When that happens, the there will be two types of blockchains in the network. Then depending on where the next mined block is attached, the longer blockchain is formed. Then network accepts the longer version of the blockchain and drops the other block.
  2. When a block is dropped because a longer version of the blockchain exists in the network, that block is called stale block/Orphan block.
  3. When a block is not propagated in the whole network and a longer version the blockchain exists in the network, it leads to dropping of the shorter chain which leads to occurance of stale blocks
  4. It is better to wait for 6 new blocks because that will ensure that the block containing your transaction is dropped.
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#3602

  1. The one that is used as a basis for the hash in the next block, will be the longest, and thus get accepted by the network.

  2. It is a block that is not accepted because another block that was created at the same time became the longest

  3. Because some times two blocks are created at the same time, and one of them has to be accepted and the other becomes stale

  4. Because then you know for sure that this is the version of the blockchain that will be accepted

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#3603

  1. Both blocks are added to the blockchain. After 10 minutes, the next block determines the longer chain. The block within the longer chain remains and the shorter chain gets removed from the blockchain and goes back to the mempool. This is called a stale or orphaned block.

  2. See 1.

  3. See 1.

  4. Wait because there could be a chance your transaction ends up in a stale block.

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#3604
  1. The network will choose the longer chain.
  2. A stale block is a block the has been rejected.
  3. Stale blocks occur when one block is chosen over another.
  4. 6 confirmations are needed before other blocks are rejected.
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#3605

  1. only one version of the block will be appended to the blockchain

  2. a stale block is a valid block that is left our of the chain

  3. stale blocks occur when a valid block is not appended to the chain because a longer chain already exists with those valid transactions

  4. the network needs to sync all blocks so they are up to date

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#3606

  1. The chain forks until the longer/more difficult block is accepted.

  2. A block that is dropped and moved back to the mempool.

  3. Happens when two miners create or validate a block at the same time.

  4. To prevent stale blocks, that is why 6 confirmations or 10min.

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#3607

6 confirmations takes approximately 1 hour. Then you can be 99.99% sure that your transaction will be immutably recorded on the bitcoin blockchain forever.

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#3608

If two miners solve a block at the same time - then can get a situation where there are two versions of the blockchain present in the network, and both are valid.
Of the two valid blockchains - it is the one that has the next block(s) appended that will become the accepted blockchain - because minors must always add new blocks to the longest blockchain (longest in terms of most POW). This means that blocks that were on the blockchain that remains smaller that are not in the accepted blockchain, become orphan blocks, or stale blocks.
Stale blocks are discarded and the transactions in stale blocks are returned to the mempool.
It is the emergence of stale blocks, and the process of discarding stale blocks with their transactions going back to the mempool that makes it important to wait for 6 or more blocks to be appended to a blockchain after the block with the transaction that we want to confirm, before confirming that transaction. In this way, we can be confident that the transaction is not in a stale block - and is probably in the valid, or accepted blockchain, because it is still having blocks added.

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#3609
  1. What happens in the bitcoin network when two miners solve a block at the same time? The blockchain splits into two valid chains which are both valid. The blockchain will continue on only one of these blocks, leaving the other to be rejected by the network and its transactions returning to the mempool
  2. What is a stale block? A block that was successfully mined but is rejected by the network because the blockchain has continued on a block that was mined at the same time
  3. How do stale blocks occur? When two blocks are mined 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? Just because a transaction is on a block that has been appended to the chain, does not mean that it has propagated and accepted throughout the network of nodes.
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#3610
  1. What happens in the bitcoin network when two miners solve a block at the same time?

The chain splits into two valid ends. The longest chain will win and the transaction of the other chain will be dumped back into the mempool.

  1. What is a stale block?

Orphaned block that was mined but get dropped since the blockchain has continued on another chain (the longest chain)

  1. How do stale blocks occur?

When two miners mine a valid block at nearly the same time.

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

Because it can become stale if there are multiple versions of the truth. It is recommended to wait for 6 confirmations.

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