Homework on Stale Blocks

[Fox_Hound]

Q1. What happens in the bitcoin network when two miners solve a block at the same time?
A1. The network waits for the next block to be mined to see which block has a longer chain.

Q2. What is a stale Block?
A2. A stale block is dropped from the chain because is was not verified with consensus and all the date in the block returns to mempool.

Q3. How do stale block occur?
A3.When two miners solve a block on the same time, the block that is not confirmed with a new block is called a stale block then dropped from the chain.

Q4. Why is it important to wait for more then one block to be confirmed when sending or receiving a transaction?
A4. to confirm the linage of the block in the chain.

[Sharon]

1. What happens in the bitcoin network when two miners solve a block at the same time?
   Both blocks are propagated to the network and accepted by certain nodes.
2. What is a stale block?
   When the following block appends to one of the two blocks the other is rejected and the transactions return to the mempool. This is called the stale block.
3. How do stale blocks occur?
   They occur when two miners solve the cryptographic puzzle in the same block.
4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
   Because your block may be a stale block and your transaction may ultimately fail.

[ChefJDaly]

1. The Chain forks temporarily and the longest chain wins.
2. A block that gets sent back to the mempool
3. When 2 blocks solve at the same time the one that is not chosen will be dropped.
4. It can take up to 6 new block confirmations added to fully confirm a transaction.

[Jelle_Buskermolen]

1. What happens in the bitcoin network when two miners solve a block at the same time?
   Their will temporarely be two chains. The one which gets adopted the fasted by other miners and becomes the longest will one and turns into the valid chain.
2. What is a stale block?
   A block which didn’t become part of the longest chain and was sent back to the mempool.
3. How do stale blocks occur?
   When two blocks are mined and added to the chain there will be two chains. The one which is build up on further, the fastest gets the longer chain and ‘wins’. The other blocks are no longer part of the chain and are sent back to the mempool.
4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
   Because you can’t be sure that your block doens’t become a stale block after one new block being mined. It can take up to 6 blocks to make sure your transaction is part of the blockchain and is fully comfirmed.

[Suleno]

1. It happens that the entire network probably will have two different version of the truth at the same time, so basically there are two different blockchain that coesist. Both blockchain are legit since the nonce of the least block is below the target.

2. A stale block is a block which is dropped, and the tx contained in it will be put again in the mempool.

3. When two miners mine a different block at the same time and propagate it, then can occur that the network will have two different version of the truth, both valid. Now when another miner come in order to mine another a block, he choose the transaction based on a blockchain, but actually there are two blockchain coesisting. Depending on what blockchain the Miner based his block, one previous block (the two that were mined at the same time) will be dropped and tx contained in it putagain in the mempool.

4. Because it might be the case that the transaction will be put again in the mempool (if it was contained in a stale block) and so basically it is like it never occur.

[IDN001]

1. The network has a fork.
2. It is a valid chain but a losing one, because there is a longer chain with valid transactions which is accepted by the network.
3. If two miners create two different block same time, then there are two versions of truth. The one which would be accepted by the other miner would have a longer chain so network accepts that one. The transactions in losing one will be returned to mempool.
4. There could be a fork. That is why better to wait until network syncs and the work would not be lost.

[athena.formosa]

1. when two miners solve a block at the same time, the minor which got chosen by the next minor that comes will decide which one gets to be in the block. the minor that did not get chosen will go back to the mempool.

2. A stale block is the block which the minor did not get chosen when two minor solved the block at the same time.

3. A stale block occurs when two minor solve the block at the same time but only one was chosen by the miner that follow. the unchosen minor then will be the shorter link and will not be chosen by the block as a result , it goes back to the manpool

4. the block will pick the longer chain so it is important to wait for confirmation that the block where your transection is has not been drop by the chain.

[DaleH]

1. When two miners solve a block at the same time, both blocks are valid and can be passed onto nodes. However, the miner that has the longer and more difficult blockchain will ultimately have their block accepted by the overall blockchain, thus, making the other miner’s block stale.
2. A stale block is a block that was initially valid but has been dropped by the blockchain.
3. Stale blocks can occur whenever more than one miner solves a block at the same time but the other miner eventually has a longer and more difficult blockchain.
4. It is important to wait for more than one block to be confirmed (6 block confirmation) when sending or receiving a transaction to ensure blocks do not become orphaned.

[Snoovy]

What happens in the bitcoin network when two miners solve a block at the same time?
The nodes closest to those miners will propagate the blockchain with those respective blocks, the situation will resolve when the next miner ads a block chain to one of these chains, the one that’s chosen will continue while the other one will be invalidated and dropped.

What is a stale block
A stale block is a block that had been invalidated because another longer versions of the blockchain exists without this block included.

How do stale blocks occur?
When two separate miners create a new valid block on the blockchain at the exact same time.

Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
Because of this situation where it’s possible that during propagation worldwide a different longer blockchain may exist which might drop your transaction if it’s in an orphaned block.

[C.shepherd]

1. Both blocks are valid and are propagated to different parts of the network. The blockchain splits into two blockchains.

2. A stale block is a block that was once a valid block on the blockchain but was then dropped by the network because there was another version of the blockchain that was longer. Transactions from the stale block are put back into the mempool.

3. Stale blocks occur when two blocks are propagated to the network at the same time and the blockchain splits into two. One block is continued and the other block is dropped by the network.

4. It’s important because there is a possibility your block could become a stale block and your transaction would be put back in the mempool. Once six blocks have been added after your block, it’s safe to assume your block is secure.

[JuniorB]

1. Both blocks will be added to the chain, but one of them will be discarded and considered a stal or orphaned block. The block wich get a new block added to it wins and the other gets discarded. So the block with the longest chain wins.
2. It is a discarded block or a dropped block, due that another block won because it had a longer chain.
3. When two blocks are added to the block at the same time, but one of the blocks get dropped because the other block was continued on the blockchain because it had a longer chain.
4. To be sure that the block will not be dropped from the chain. 6 confirmation is needed to be sure.

[DavidV]

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

One of two will be dropped. The one who is added to next block/blocks first wins and the other one get dropped. The longest chain wins. This is calledma stale block.

2. What is a stale block?
   A block that has been discarded from the blockchain.

3. How do stale blocks occur?

It occurs when two miners mine a block at the same time.
If a block is not part of the longest chain in the blockchain it gets dropped from the blockchain and becomes a stale block.

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

Because it can turn out the confirmaton of your TX was confirm in a stale block which is then later dropped from the blockchain. This makes the transaction unconfirmed and is returned to the mempool.

[DavidV]

What happens if two different miner pick different valid blocks at the same time to create the new block with? Is this why 6 confirmations is needed as there might be up to 6 different versions fo the blockchain until only one is the longest? Or Is this impossible. After mining a block does everyone have to wait out the whole 10 minute before they choose a validated block and then the one which was chosen the quickest wins and only one can win? This part sill confuses me…

[Maki]

This article explains in details about stale blocks https://criptomo.com/two-simultaneous-blocks/

[Mohammed_Al_Arab]

1- When two miners solve a block at the same time, we temporarily have two versions of the blockchain until new block are added to one of them. Then the longer chain prevails, and the block added to the shorter chain is dropped.
2- A stale block is the block that was added and then dropped from the blockchain as explained in question 1.
3- It occurs when it is in the shorter chain, and so it is dropped and called stale or orphaned block.
4- It is important to wait so that you can be sure it will not be dropped from the chain as a result of simultaneous mining and block solving.

[tenbad]

1. The longer of the two chains is accepted into the blockchain; the shorter one is discarded and returned to the mempool.

2. The shorter block which gets discarded is a stale block, the other block produced at the same time takes its place.

3. Two blocks were produced (more or less) simultaneously but one is dropped in favor of the longer block. The transaction then becomes invalid until processed later.

4. After only one block, the transaction may appear valid but could still eventually be dropped in favor of another block. Waiting for a number of transactions means that this issue will already have been resolved by this time; after 6 confirmations the transaction can be considered definitively accepted into the blockchain.

[shane23]

1. whichever block gets used or added to the chain first by another miner and the longest chain gets used.
2. a valid block on the chain that does not get used.
   3 when two or more miners finish a block at the same time .
3. to verify that your transaction is on the blockchain, the more confirmations the less likely to be dropped from the chain.

[Piers_Sciolti]

1. They are both used until another miner adds to either one, and the first miner to get 6 blocks added after his block wins and his block is confirmed.
2. Stale blocks are blocks that are valid but have been dropped by the network as they don’t have as much proof of work as the other blocks.
3. ^ When another miners block has more proof of work than yours so your block isn’t used.
4. Because it takes 6 blocks after the original block to be confirmed.

[Piers_Sciolti]

3. And sent back to the mempool*

[Skatecat]

1. When 2 miners solve a block at the same time it effectively means the chain will split and the next block to be mined will only use one of the 2 blocks.
2. A stale block is one that gets rejected out of the chain because it no longer forms a part of the longer variant of the blockchain.
3. Stale blocks occur when 2 miners both produced a valid block into the blockchain at a similar time but whichever version of the blockchain manages to propagate first will be accepted as the valid blockchain and the other one gets left out of the new blockchain. The block that gets left out is the stale block.
4. It is important to wait for more than one block to be confirmed so that you dont end up producing stale blocks where your transaction might be reversed and sent back to the mempool.