Homework on Stale Blocks

[ivan]

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?

[marsrvr]

[bit]

1. 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.
2. 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.
3. 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.
4. 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…

[Baidis]

@ivan

• What happens in the bitcoin network when two miners solve a block at the same time?
• What is a stale block?
• How do stale blocks occur?
• Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?

1. The chain forks temporarily

2. A block that gets put back into mempool in favor of chain with more POW

3. Stale blocks occur after a fork is resolved with a longer chain

4. In case of a stale block occurring.

[Cathy]

1. When 2 miners solve a block at the same time the block in the longest chain wins and the other block is discarded and considered a stale or orphaned block. All the transactions are returned to the mempool.
2. A stale block is the block that was in the blockchain but then dropped because another block that was produced at the same time was part of a longer chain.
3. Stale blocks occur when a block was valid for a while because 2 were produced with the same version of the truth but then dropped because the blockchain continued on another block.
4. It is important to wait for 6 confirmations to be sure that the block your transactions are in is not dropped from the chain.

[Alko89]

1. The chain splits into two valid ends.
2. A block that was dropped from the blockchain due to an occurrence of a fork.
3. They occur when two miners mine a valid block approximately at the same time.
4. In case of the occurrence of two chains, once one chain is accepted as the main chain, the transactions of the loosing chain are returned back to the mempool.

[Goosie]

1. What happens in the bitcoin network when two miners solve a block at the same time?
   The chain splits into two chains. The longest chain will win, the transactions of the other chain will be dumped into the mempool.

2. What is a stale block?
   The block of the shortest chain after a fork, which will be moved to the mempool

3. How do stale blocks occur?
   After a fork. Its the block with the shorthest chain.

4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
   How more confirmation how better. Someone could maybe double spend his utxo.

[tvnaresh]

1. An orphaned or stale block is created as two versions of truth results is possible. The third miner who chose whatever the version of truth makes that blockchain as lengthy resulting in other version to be dropped causing stale block.
2. An orphaned block which is a valid block but dropped from blockchain as there two versions of truth due to simultaneous mining.
3. Stale blocks occur as only version of blockchain is accepted by network by dropping other version of truth. See point 1.
4. Because it can possibly become stale if there multiple versions of truth. 6 confirmations is recommended.

[Lynn_Qi]

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

The less difficult one has to be dropped, all transactions in that block are put back to mempool.

2. What is a stale block?

A stale block is the valid block, but not accepted by the network, has to start over again.

3. How do stale blocks occur?

Because of physical distance in the globe network, two miners slove different block at the same time, but not knowing the other one exists.

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

To avoid the stale block or orphaned block occur.

[mikekgs]

1. Since it is impossible the nonce would be the same some nodes would contain slightly different versions of the block chain and propagate them.

2. A stale, or orphaned block that had been accepted and caused a fork in the blockchain, but that the network has now rejected.

3. Stale blocks occur when there is a fork in the network due to two miners solving the problem at the same time with different blocks and eventually the network rejects one of the blocks as new blocks have been mined without that in the chain.

4. Because it is possible that a fork has occurred. The further back in the blockchain the block is though the less likely it is that the block was stale.

[Jshanks21]

1. The nodes closest to each miner will receive different versions of the recently appended blockchain until the next block is mined. Once a new block is mined, it will be appended to one of the two chains. Whichever chain receives the new block will be longer and accepted as true by the network. The other block will be invalidated and return to the mempool until it is mined again.

2. A stale block is a block that was not confirmed onto the blockchain.

3. They occur when a block is invalidated due to alternative blocks on a new, longer chain being mined faster and accepted by the network. E.g. Two miners mine a block at the same time, but only one can be accepted as true on the network. Whichever receives a new appended block faster is considered longer and, hence, the true chain.

4. Because your transaction could be left stale or orphaned if it does not have enough confirmations to secure it in the blockchain.

[StevenHodlmans]

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

Both blocks will be transmitted to the other nodes. For a while 2 different versions of the chain will exist untill miners mine the following block creating a longer chain in one of both. the longest chain wins and the other ‘chain’s’ transactions are invalid. This will create a stale block.

2. What is a stale block?

See 1

3. How do stale blocks occur?

Due to 2 miners mining a block at the same time, one of both will go stale.

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

To be sure you TX is accepted and not dropped due to stale block.

[Capaburro]

1. What happens in the bitcoin network when two miners solve a block at the same time?
Both block will start propagating through the network until 1 of the 2 blocks will be refused because it is mined on the shortest chain. (only the longest chain wins)

2. What is a stale block?
A block that was mined correctly but eventually was not on the longest chain.

3. How do stale blocks occur?
When some miners mine a block at the same time (only 1 block can win).

4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
When your transaction is part of a stale block, it gets moved back into the mempool so the confirmation will be 0 again.

[Shivani_Shah]

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.

[RichieR]

1. When two miners solve a block at the same time the bitcoin network continues to propagate until one blockchain is longer.

2. A stale block is a block that was at one time in the blockchain but dropped because there were other blocks in the blockchain longer without those blocks inside them.

3. Stale blocks occur when two blockchains are built simultaneously and one of those blockchains does not get used.

4. It is important to wait for more than one block to be confirmed to ensure that your block is used and not dropped from the blockchain.

[paschkka86]

1. Both blocks will be added parallel to the last block ( kind of a fork). The block after will decide which is the right path, by making the chain longer.

2. A stale block, is a block which was added to the chain, but was removed, because the other chain was longer.

3. Happens if 2miners solve the puzzle at the same time. So both blocks are added parallel to the block, but one chain is not used.

4. Because the transaction could be in the stale block. So they chain won´t be used and the transaction goes back into the pool.

[Dave_Simo]

1. Those blocks start competing to become the largest blockchain, the block the next miner picks will become the main blockchain making the other block a stale block.

2. A stale block is a block that was dropped from the main blockchain.

3. A stale block occurs when a miner chooses a block over the other.

4. Because stale blocks can occur and by waiting 10 mins you can be sure your TX goes through all the way.

[dave-dave]

• What happens in the bitcoin network when two miners solve a block at the same time?
  The longer chain will win. the block from the shorter chain will be dropped and send back to the mempool.

• What is a stale block?
  Dropped block that returned to the mempool.

• How do stale blocks occur?
  Two miners propagate a legitimate block to the network.

• Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
  This is the best practice to make sure that our block was applied to the chain and is not an orphan block.

[rakeshrinawa]

1. When it happens, the miners/ users keep on mining the first block they receive, but once next block on one chain is received, the shorter chain’s block is dropped.
2. It’s a block that was added to the blockchain at some time but got rejected when another larger chain with more proof of work was mined.
3. When 2 miners finds a new block almost at the same time, stale blocks occur.
4. It’s important because there may be a case that our transaction has been included in a stale block and may not be included in the reorged blockchain and we may lose the bitcoins as receiver. But in most of the cases of the cases if we are paying a higher fee then, there is a high chance that it will also be included by the miners in the reroged chain. Even if it hasn’t been for some time due to non-propagation, we can transmit the transaction to the different nodes so that it is mined by the new chain.

[mszp]

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

They are propagating the two verions of the valid blockchain.

2. What is a stale block?

It is a block which was in the past in the blockchain, it was valid, but in the end it was droped out of the network because there was another valid block with longer PoW chain, what means more miners built the network on it.

3. How do stale blocks occur?

More miners choose the other block as the original and that creates stale blocks which were chosen by less amount of miners.

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 your transaction will be in the stale block or not. Waiting six confirmations should be enough to be ensured about validation of the transaction.