Homework on Stale Blocks

Blockchain and Bitcoin 101
#2149
  1. What happens in the bitcoin network when two miners solve a block at the same time?

Both blocks are valid until the next miner basing his block with one of them. In that case, the unchosen block will be drop from blockchain and all the transaction in that block will be returned to Mempool.

  1. What is a stale block?

A stale block is a valid block but dropped from blockchain due to lack of block propagation/continuity.

  1. How do stale blocks occur?

When half of the network has one version of truth and the other half has another version of the truth. However, they both have a valid block but different transactions.

  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 is not in a stale block.

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#2150
  1. If blocks are solved simultaneously with different nonces leading to different hashes, these separate hashes will be transmitted at the same time to different nodes. Depending what solved version each specific node gets it will act as that solved version is the correct one.
  2. A stale bock occurs after two versions of the same block are solved and are being broadcasted to the network as such. Since only 1 block can exist, a stale block is the block that ends losing out and not making its away onto the blockchain over the next few confirmations.
  3. Once more than 1 versions of the solved block are being transmitted to the nodes and the network, each node will believe whatever block is the longest. Since they are the same length, and each version of the block has a different hash number, the block that will survive on the chain will be determined with which version of the hash number the next mined block used to find that next block’s solution. This will get transmitted to the nodes and the network again and since the chain is longer, it will be consider the more validated version.
  4. The current recommendation is to wait for 6 confirmations. After each block is mined, the new block is again broadcasted to the network and the nodes. After this length and how many times the nodes have checked the network, the work will be propagated through enough nodes to make it a statistical impossibility that there will be another block mined that had forked 6 blocks earlier with different transactions through the next 6 and a future mined block hit the system that will be the longest and hence making the other blocks stale.
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#2151
  1. If two minors write a block at the exact same time the network will pick the longest chain which is closer to the target number, the shorter chain/farthest from the target number will be dropped.
  2. A stale block is a block that has been dropped from the chain.
  3. When a block is dropped or when a block is created too quickly it becomes a stale block.
  4. Confirmed TXs contain 6 confirmations or 6 blocks after the block with your TX or hash if you’re a minor, otherwise there still remains a possibility of being dropped.
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#2152
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    They are each accepted and broadcast to the network. Nearby nodes get updated copies of the blockchain sooner than faraway nodes. So for example one node in India might accept “Pria’s” block while a node in Mexico accepts “Roberto’s” block at the exact same time. During the next 10 minutes both chains are considered valid but as soon as another block is added to one of the ends of this split blockchain, the longest chain will become the valid blockchain and, the block on the shorter chain will be abandoned and its transactions returned to the mempool.
  2. What is a stale block?
    The abandoned block, also known as an orphaned block.
  3. How do stale blocks occur?
    When new blocks won’t attach to the end of a copy of the blockchain because there are longer versions of the blockchain available.
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Because any transaction might wind up in a stale block and then be relegated back to the mempool where it will wait until forged into a block once more. This can take some time and if there is another tie, it can take even more time. That is why, with Bitcoin, you should wait for 6 or more valid blocks before you are sure of a transaction going through.
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#2153
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    There becomes two valid blocks getting spread through the nodes and eventually a miner will choose one to mine on and only the block belonging to the longest chain and most proof of work will be accepted by all nodes.
  2. What is a stale block?
    A stale block is a block that was valid at a moment in time but was “pushed out the block” by a more accepted and used block on the chain
  3. How do stale blocks occur?
    As a result of two blocks happening at the same time. one becomes part of the block and one becomes stale.
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    because your block might be a stale block but 6 blocks confirmed is a long enough block and enough PoW done to feel confident that your block is not a stale block
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#2154

  1. Both miners start append block to the chain then propogate the new chain on the network. Eventually, one chain is chosen, the longest, which has highest difficulty level. The blocks on the dropped chain are returned to the mempool.

  2. A stale block is a block that has been dropped from the network.

  3. Stale blocks occur if it has been appended to the chain, but that version of the chain has been superceded by another version of the chain which has a higher difficulty level.

  4. To ensure that the block is valid and that the transaction is not on a stale block. After various blocks have been confirmed, 6 is a good number, it is certain the block is confirmed.

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#2155

  1. These 2 blocks are spread through the network. The first of these blocks to be added to will become the longest and therefroe newly accepted and mined upon blockchain. the dropped blocks will be added back to the mempool

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

  3. Stale blocks occure when multiple blocks are mined at the same time with valid nonces, eventually one block will become longer and all the newly added blocks not accociated with the network will be dropped and need to be remined.

  4. Because there is a chance that the confirmed block could become stale.

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#2156

1. What happens in the bitcoin network when two miners solve a block at the same time?
a. Assume 2 miners; Miner A and Miner B
b. The block for both miners are considered ‘confirmed’ as they are in the blockchain
c. Depending on the propagation of each miners block, other miners ‘globally’ can try to solve either Miner As block, Miner Bs block or both miners block if they want to (also dependant on whose blockchain, Miner As or Miner Bs blockchain version they receive)
d. The first ‘global’ miner to add a block in either of the two miners block, the network will consider the ‘truth’
e. i.e. Miner X appends a block on Miner As block but is the first miner to add on either Miner As and Miner Bs block.
f. This results in the network choosing Miner As block as the ultimate truth
g. Miner Bs block will be dropped and the transactions inside moved to the mempool.

2. What is a stale block?
a. Blocks that were in the blockchain at one point in time but were dropped due to;
i. Another version of the blockchain was longer
ii. That blockchain did not have that particular block inside its version of the blockchain.

3. How do stale blocks occur?
a. When multiple miners solve a block at the same time, it creates multiple versions of the blockchain.
i. As there can only be 1 version of the blockchain, other versions need to be discarded
ii. The network will consider the longest blockchain (most PoW) the ultimate truth.
iii. The blocks from the other versions will be dropped
b. Blocks that are produced prior to 10 mins
i. Due to not completing its propagation, an older block might be dropped due to a newer block being appended into the blockchain

4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
a. In case of orphaned/stale blocks occurring
b. Best practise is to wait at least 6 confirmations

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#2157

  • What happens in the bitcoin network when two miners solve a block at the same time?
    Two blocks will then be created.

  • What is a stale block?
    A stale block is when one of those two blocks that were creaTed at the same time is used to creat the next block and then the other block that was created at the same time will be dropped from the network and invalidated, causing the TXs in the stale block to go back to the mempool.

  • How do stale blocks occur?
    Stale blocks occur when one of the blocks that was created at the same time is picked up by the next confirmed block and the block that wasn’t picked up will become stale or orphaned.

  • Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    Because you need to make sure that the block with transaction doesn’t get dropped from the network due to the possibility of it being orphaned. It’s a good rule of thumb to wait 6 blocks for confirmation

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#2158
  1. When two miners solve a block at the same time it creates two versions of the blockchain. However, eventually, one of the versions will become “stale or orphaned”. This means that one version will always win - the longest version. It is considered that a miner should not consider their block to be confirmed to the blockchain until six other blocks have been appended.
    2.A stale block is a block that correctly had the hash of the previous block, the hash of the block they’re looking to append and have solved the nonce, but was dropped from the blockchain. Theoretically, the block has been temporarily added to the blockchain, but it won’t be confirmed until six other blocks have been added to their block. Stale blocks are dropped from the blockchain.
  2. There is a possibility of two miners adding two blocks to the blockchain at the same time. Until six blocks have been added after your block it shouldn’t be consider your transaction has been confirmed. All transactions on a stale block are moved back to the mempool.
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#2159
  1. There can be only one. Another minor will come along and choose one block, invalidating the other and returning all it’s transactions to the mem pool.
  2. A stale block or orphaned block is a block that has been dropped from the blockchain.
  3. When two blocks are added to the blockchain they are essentially competing. Another block will be added to one which invalidates the other.
  4. Because the block that your transaction is sitting on may become stale or orphaned.
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#2160

What happens in the bitcoin network when two miners solve a block at the same time?
one will win eventually, the longest blockchain will win. One blockchain, the shortest will be orphaned and dropped.

What is a stale block?
orphaned block on the shortest blockchain where there has been another version of the truth that has been accepted by the decentralised nodes.

How do stale blocks occur?
by two version of the truth or blockkchains being produced or propagated in the network and maybe blocks being produced prior to the 10 mins. Blocks being produced prior to six confirmations and prior to the correct version of the truth having the chance to propagate through the network.

Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
to see if that chain has been accepted by the decentralised network. The more confirmations the longer the block-chain length. The longest block-chain is the one that is accepted as the greatest version of the truth so miners extent it more by resolve the nonce for the next block reward

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#2161

Homework on Stale Blocks

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

Blocks first reach the nodes in the network that are closest to them geographically.

In this case, where we have two blocks being produced and appended to the blockchain in different parts of the world, we temporarily have two versions of the truth.

2. What is a stale block?

These arise through the process outlined in the previous question, but they get dropped by the network before they are able to be confirmed, resulting in the transactions that they contained being returned to the mempool, in preparation for eventually being added to a later block.

3. How do stale blocks occur?

The next block can only append to one of the two versions of the blockchain, rendering the other block redundant (this becomes the stale block), whereas the longest chain remains, as governed by the bitcoin protocol.

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

This is because the new block could potentially become a stale block, if another block was produced at the same time elsewhere in the network - if this was to happen, the transaction would be returned to the mempool, which, upon being added to a fresh new block, would allow for that transaction to be double spent.

In the bitcoin network, transaction must be verified six times before it is considered confirmed - this means that by that point, six blocks sharing a chain of hashes linking back to the block which contains the transaction have successfully been appended to the blockchain.

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#2162

What happens in the bitcoin network when two miners solve a block at the same time?
The blockchain will temporarily fork into two separate blockchains until a final winner emerges.

What is a stale block?
A block that was dropped from the ledger and put back into the mempool for another try.

How do stale blocks occur?
A valid block that was at one time in a fork of the blockchain that was trying to be confirmed but it’s fork lost out to a competing fork, and therefore the block was dropped from the ledger.

Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
To be certain that the block with your transaction doesn’t get dropped later due to a competing fork in the blockchain.

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#2163

A transaction is actually confirmed as soon as it gets on the blockchain and each subsequent block added is another confirmation. :slight_smile: If a transaction gets dropped it actually gets unconfirmed.

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#2164

1.In bit coin network when two miners creates blocks at the same time, the blocks are propagated to other nodes and when the next the next miner creates a block, the version he chooses is taken as the true version and the other block is put back to the mempool.
2.The block which is confirmed by some node but is not the longest version of the block chain is called stale block. The transactions in this block is returned to the mempool.
3.Stale blocks occur when two or more miners solves the cryptographic puzzle at the same time and creates blocks at same time. This leads to two versions of chains propagating in the network
4.It is important to wait for more than one confirmed block because stale blocks may occur.

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#2165

1 the miner that gets mined next is kept and the other is a stale block
2. a stale block is a block that was on the blockchain but was rejected and put into the mempool
3. whenever 2 blocks come out at the same time
4 in case of a stale block

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#2166

1. What happens in the bitcoin network when two miners solve a block at the same time?
One of the miners will eventually win with the longest blockchain winning. The shortest section of the blockchain will be orphaned and become a stale/orphaned block and all the transactions within it sent back to the mempool.
2. What is a stale block?
A stale block is a dropped block that has been returned to the mempool.
3. How do stale blocks occur?
Stale blocks occur when two different miners mine different blocks simultaneously.
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 in order to reduce the risk of transaction being placed on a block that becomes a stale/orphaned blockchain section.

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#2167

  1. If two miners solve a block at the same time with valid nonces, they are both added to the blockchain and are still “unconfirmed” until other miners decide which longer chain of blocks to hold as the truth. Generally you want to wait for 6 confirmations or 6 new blocks to know your transaction was and will be accepted as the truth. There can’t be two circulating versions of the truth so the unclaimed block and its transactions will be put back into the mempool once one of the chains is decided upon.

  2. A stale or orphaned block is a block that was rejected by the network even though it had a correct nonce and valid transactions. These valid transactions that weren’t included in the appended block added back into the mempool.

  3. A stale block might occur if it was appended at the same time as another slightly different block. Other miners in the network continued on with the alternative block making it the longest chain and therefore the agreed upon truth, invalidating the prior block and making it an orphaned block.

  4. Because your transaction might end up being in a stale block and then the transaction isn’t truly confirmed. You should wait for 6 block confirmations to know your transaction is truly confirmed.

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#2168
  1. Longest chain wins.
  2. A block that has been dropped.
  3. When 2 miners solve at the same time.
  4. Should wait for 6 confirmation. This ensures that it is not dropped and sent back to mempool.
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