Homework on Stale Blocks

[bigez]

1. It is up to the next miner which block they use, depends on which version of the truth they get. The longest blockchain with more PoW wins while the other block gets dropped.

2. A stale block is a dropped block, a valid block that was dropped by the network since another miner had mined one at the same time and more nodes used this version of the truth, the tx in a stale block go back to the mempool.

3. When two miners mine a block at the same time, they are both valid blocks since they fulfill the requirements to be appended to the blockchain however one will have to be dropped to preserve one version of the truth.

4. In case the block where your transaction is gets dropped and becomes a stale block, usually the standard is to wait for 6 confirmations, thus 6 blocks added from the one that contains the transaction.

[Lisalazuli]

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

Both blocks are added, however both will propagate to different nodes or geographic parts of the network, so if there is a block A and B, some nodes will form a chain with A and some with B. Hence there is an inconsistency in the network.
2. What is a stale block?
If different parts of the network have added two different simultaneously produced nodes or A and B, it all hinges on which chain the next winning block is added to. If the next block produced is called C and it is added the B, then A becomes stale as it is part of a shorter chain and is just rejected and it’s transactions sent back to mempool.
3. How do stale blocks occur?
They are not propogated as fast through the network as a simultaneously produced block and hence future blocks are less likely to be connected to them via their hash.
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 become stale or orphaned and your transaction will return to the mempool and be unconfirmed

[Fabrice]

So you have 2 valid versions of the blockchain going around. Then it mostly depends on the next miner on wich one he mines the next block. Wich makes 1 version longer than the other. You don’t need 6 confirmations to be sure but it’s good practice. For example if you sell a house, I would wait for 10 confirmations. If I you sell a giftcard of 20dollars, I would be happy with 2 confirmations.

[timl]

@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. A fork happens, two chains now exist. As only one chain needs to exist, the longest one will get accepted as the correct one.

2. A stale block is a block that was not included in the chain.

3. Some miners can mine a block at the same time and cause two versions. When one chain version succeeds another version, the block on the shorter version becomes stale, the block is still valid but no longer relevant.

4. As when the block is mined, there’s no guarantee that this chain won’t get replaced by another parallel chain and the block is going to get stale.

[Falkon]

1. The chain splits to two different chains, the next miner to add a block on one of the parallel blocks will make the previous block the real block and the other parallel chain will not be used (as it is shorter chain) and all tx on the last block will be added back to the mempool.
   2.The block from the shorter chain that got dumped and all tx are sent back to the mempool is called a stale block or orphanage block.
   3.When two miners solve a block at the same time there will be a split in the blockchain (called a fork) one of the chains will become the real chain and on the shorter chain the last block will become a stale block.
   4.Once you wait more than one block you make sure your tx was not on a stale block.

[Kerry_Bul_run]

Stale blocks

1. When two miners solve a block at the same time, two different versions of the blockchain are created. The first of these to be selected to create the next block is longer and becomes a part of the permanent chain.
2. A stale block is the orphaned block from the smaller chain.
3. Stale blocks occur when two miners solve the nonce at the same time and leave a shorter block chain.
4. It is important to wait because a single confirmation could be inside a stale block and the transaction may be returned to the mempool.

[CocoaCrypto]

1- One block will end up getting dropped because there cannot be 2 versions of the truth.
2- A stale block is a block that has been dropped from the chain and returned to the mempool.
3- Stale AKA Orphan blocks happen when 2 miners have a block to append to the blockchain (so they’ve solved the nonce puzzle and their hash is equal to less than the target number), but another miner adds a block to only one version of those truths- i.e. only one of those blocks, thus making it part of a longer chain. The network will always pick the longest version of the chain, which means the other block will be dropped and put back into the mempool. The dropped block is the “stale block.”
4- Well, in the previously mentioned scenario, both blocks have been confirmed, but only one of them will make it into the chain, so it’s best to wait until more blocks have been added after a confirmed block to make sure that block doesn’t end up being dropped.

[David_Walsh]

@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 2 blocks are both valid and will get propagated by different nodes on the network and 2 different versions of the blockchain will exist temporarily.

2. A stale block is a valid block that was part of a shorter version of the blockchain but was disgarded in favor of another longer version of the blockchain which has a higher proof of work.

3. When there are 2 blocks that have been mined at the same time creating 2 versions of the blockchain, then different miners may attempt to mine a new block based on the 2 previous blocks that were created at the same time. When the first new block is mined it makes 1 version of the chain longer than the other and the block on the shorter chain is discarded and becomes a stale block and it’s TXs go back to the Mempool.

4. It is good practice to wait for 6 confirmations to insure enough time for the nodes in the network to get in sync so that you know the block that your transactions are in has not been orphaned from the blockchain.

[gllan005]

1, The will split in two until eventually another miner adds another block and the longer chain gets propagated while the shorter chain moves back into the mempool.
2. The blocks that were confirmed later gets dropped from the concesus blockchain.
3. When the block chain split in two from multiple miners appending block around the same time then then shorter branches get dropped.
4. To reduces chances of becoming a stale block.

[wafflemakr]

@Jmsn

They occur when nonces in different blocks generates hashes that are valid at the same time. Which means that they also have good transactions from the mempool, although not necessarily the same.

Hi there! Here you explain that two valid blocks are added to the blockchain, but when does one of these blocks become stale?

[Lacho]

1. What happens in the bitcoin network when two miners solve a block at the same time?
The block with more blocks win. AND the stale block goes to the mempool.
2. What is a stale block?
A block that was drop because other block was created and has more blocks.
3. How do stale blocks occur?
Because was created at the same time of another one but dropped when the the block chain continues with another block.
4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
We need to wait at least 6 more block con confirm that the transaction were not dropped.

[Bren509]

1. If a block is solved at the same time with two different computers, the two versions of the blockchain are propagated throughout the network until the next block is solved. When this happens the version of the previous block that the latest block had in its database will be the will make it the longest chain and the network always selects the longest chain to continue.
2. Stale blocks are the ones that were created at the same time as another but did not get selected due to being a shorter chain.
3. Stale blocks occur once the network resolves the permanent chain, then returns the leftover transactions to the mempool.
4. Always wait for more than one transaction in case your transaction happens to be in a stale block or one that does not get selected by the network.

[paul0]

1. What happens in the bitcoin network when two miners solve a block at the same time?
   Two versions of the blockchain is created: one blockchain with the block of miner A and another blockchain with the block if miner B.

2. What is a stale block?
   It is a block that has been dropped because if was on a shorter blockchain.

3. How do stale blocks occur?
   Stale blocks occur when there are more than 1 version of the blockchain (2 blocks created at the same time) and a miner creates a new block. This new block will append to one of the available version of the blockchain and the other version of the blockchain will be disregarded for future mining, causing blocks on the shorter blockchain to become stale.

4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
   It ensures that the transaction has actually been added to the blockchain and is not in a stale block or going back to the mempool.

[ashishc]

• What happens in the bitcoin network when two miners solve a block at the same time?
  There will be two versions of blockchain (truth) but eventually the longest blockchain will be considered and the smaller chain will be dropped and is called as orphaned block.

• What is a stale block?
  Stale or orphan block is the smaller chain which is dropped by the nodes beacuse other block produced by the miner forms the longer chain.

• How do stale blocks occur?
  When there are two versions of truth and the next miner decides to pick any block which makes it a longer chain . The shorter chain will be dropped by the nodes and all transaction goes back into mempool , this is also called stale block.

• Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
  It is advisable to wait for the 6 confirmation atleast to be certain the transactions are not dropped back in the mempool.

[MarkM]

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

The nodes start propogating the block from the closest miner. Now the nodes have two
versions of truth. Both blocks transactions and nonces are valid. When a new miner adds
a block to one of the miners blockchain the chain is more difficult than the other miners
blockchain, and therefore makes the chain valid. The network always excepts the blockchain
with the longest proof of work. All of the losing miners transactions will be returned to
the mempool.

What is a stale block?

A block that is dropped from the blockchain because there is a block with a different
version of the truth that got accepted to the blockchain.

How do stale blocks occur?

They occur when two blocks are mined at the same time and only one version of the blockchain is appended to the network.
The blocks that are not appended to the network are dropped from the blockchain and are called “stale” or “orpaned” blocks.

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

Waiting gives you the assurance that your block will not be dropped from the blockchain due to another miner
mining a block at the same time and his/ her block getting accepted to the blockchain over yours.

[Tristan]

QNS 1. What happens in the bitcoin network when two miners solve a block at the same time?
The bitcoin network will have two nodes propagating the block closest from the miner. It will have two versions of truth now. Both of them are valid and has their own chain. However, the network only adds the longest chain and validate. The one with the shorter chain will be forfeited and return back to the mempool.

QNS 2. What is a stale block?
A stale block is a block dropped from the blockchain as it loses out to the one that is accepted to the network.

QNS 3. How do stale blocks occur?
Stale blocks occur when two blocks are mined and added to their own chain of network. The one which dropped from the network due to it having a shorter cha is how stale blocks occur.

QNS 4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
It is important as the block may return back to the mempool due to it belonging in the shorter confirmed chain which loses out to the longer chain of blocks. By waiting, we will be assured the block is in the right chain and it is confirmed.

[Jmsn]

Hi wafflemakr, thanks for pointing that out.

A block becomes stale when the other leg of the chain keeps getting added with new blocks, thus becoming longer, and the ones that duplicated the chain are eventually dropped.

[cryptomarls]

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?

A1. There will be 2 versions for a while on the blockchain, eventually the miner with the longest chain will win and the other block will be rejected by the network.

A2. A stale block is a number of blocks that were on the blockchain as verified for a period of time, but then got dropped as another version on the blockchain that is longer got verified. The network always chose the longest chain.

A3. Stale blocks occur because a longer version of the blockchain presents itself and therefore wins over the stale blocks.

A4. Its important to wait for more than one block to be confirmed (best practice is 6) in case your block or some appended blocks get cancelled and rejected.

[ambient.coins]

1. What happens in the bitcoin network when two miners solve a block at the same time?
   When two miners solve a block at the same time, both blocks will be transmitted to the other nodes on the network. For a period of time 2 different versions of the chain will exist until miners mine the following block creating a longer chain. The longest chain wins and the other chain’s transactions are invalidated. This creates a stale block.
2. What is a stale block?
   Stale blocks are blocks that were mined correctly but are no longer part of the current best blockchain because they were overridden by a longer blockchain.
3. How do stale blocks occur?
   Stale blocks occur when two seperate blocks are mined and appended to the blockchain at the same time. After additional blocks are mined and added to the blockchain the blocks representing the shorter change are invalidated and removed from the blockchain creating stale blocks.
4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
   To ensure that your transaction is permanently accepted into the blockchain and not included in a stale block it is best practice to wait for 6 confirmations to be completely sure that your transaction is confirmed.

[AJade]

1. What happens in the bitcoin network when two miners solve a block at the same time? Both of their confirmed blocks gets broadcast to the nearest nodes around them. They coexist until a third miner appends a second block and then that longer chain propagates and overrides any shorter chains.

2. What is a stale block? A block that was once confirmed by some nodes but were then dropped because a longer chain existed.

3. How do stale blocks occur? When propagation isn’t fully completed in the network and other miners appended a longer blockchain.

4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction? To ensure your transaction isn’t in a chain of blocks that become dropped from the network.