Homework on Stale Blocks

Blockchain and Bitcoin 101
#4054

When two miners solve a block simultaneously, some miners start working on one, while some work on the other, depending on which information they received first.

A stale block is a block that was removed/dropped from the blockchain.

A stale block is a valid block that was created at the same time as another, but failed to be part of the longest PoW chain, so was removed from the blockchain. All txs from this stale block were put back into the mempool.

It is important for more than one block to be confirmed when sending-receiving because there is always a chance that your transaction ended up in a stale/orphaned block.

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#4055
  1. What happens in the bitcoin network when two miners solve a block at the same time?

There will be 2 versions of the blockchain, eventually the longest version will be maintained and the other one will be become stall and the transactions needs to be added to the mempool again on the nodes.

  1. What is a stale block?

this is a block that was eventually and finally NOT confirmed or rejected by the nodes because another longer chain was confirmed or accepted by nodes as the correct one, it becomes an invalid block.

  1. How do stale blocks occur?

only version of the blockchain will be accepted, it will be the longer version of the blockchain. If a version of the block chain is discarded, because it is shorter than another version of the block chain it becomes orphaned or know as a stale block and will not be accepted by the network.

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

multiple, 6 or more, confirmations are required to confirm a block of transactions, so if you do not wait for enough confirmations and assume transaction is confirmed it may actually not be confirmed and will not be seen as a valid transaction

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#4056
  1. Both get confirmed by some nodes. One, or even both of them might get more blocks appended, but that is unlikly because of the 10 minute delay. When a node has to decide, which blockchain is “the truth” it always takes the longer one
  2. The block which gets thrown out, even though it was confirmed at first by some nodes
  3. See 1
  4. Because it increases the liklehood of beeing truly confirmed and not becoming a stale block
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#4057

  1. When two miners have solved an valid block at the same time, there are two versions of the truth, both of which are completely valid. When the block is solved and appended to the blockchain, other nodes in the network will fetch the new block and miners will begin working on the next block. When the miners begin to work on the next block, some miners will be working on one version of the blockchain and others will be working on the other. The blockchain which will ultimately be seen as the consensus blockchain will be the version that the next miner who wins the block was working on. This is due to the fact that it has greater ‘proof of work’, which will be seen as the true version of the blockchain. The block/s from the other chain will be invalidated, and the transactions from within that block will remain in the mempool until a miner places them in a block (unless the prevailing chain included those transactions in it).

  2. A stale block is a technically valid block, yet doesn’t remain validated as the version of truth in further blocks on the blockchain. This means that on the true consensus blockchain, data from stale blocks never happened until they are submitted to a block on the true consensus blockchain.

  3. A stale block occurs when it becomes part of a version of a blockchain which inevitably is not the version which is believed to be consensus by the public true blockchain. This happens when two miners solve for a block at the same time, and the stale block version of the blockchain runs out of miners to work on it, as another version has a greater proof of work.

  4. It is important for there to be more than one confirmed block when sending or receiving a transaction, as it is possible that data from one block will be invalidated later down the track if miners are working on a different version of the blockchain. If a confirmation of only one block is sufficient, perhaps another miner solved for a block at the same time and then miners worked on that one instead of the ‘falsely confirmed’ block. This means that in the consensus blockchain, the transaction perhaps never occurred.

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#4058

  1. When two miners solve a block at the same time they kind of fork the chain, depending on the next mined block choice to validate one of these and dump the other.

  2. A stale block appears as a consequence of blocks being mined at the same time.

  3. A block becomes stale if the chain grows in other simultaneously mined block.

  4. It is important to wait for more than one block to be confirmed when sending or receiving a transaction because it allows checking if the transaction isn’t done in a stale block.

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#4059

  1. Two versions of the truth are created, however only one can survive. The winner is decided by which other miners chose to create block to as the longest chain will be allowed to propagate throughout the network.

  2. A stale block is a block which is dropped by the network. Including all of its transactions written to it.

  3. Stale blocks generally occur when a longer chain is chosen over a shorter chain, all the blocks belonging to the shorter chain are dropped and become stale blocks.

  4. It is important as this reduces the amount of stale/orphaned blocks occurring over time, this stabilizes the network in the long run.

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#4060

  1. The network will allow it temporarily but ultimately whatever chain is the longest will be accepted and the other dropped. This is usually 3-6 blocks after two miners solve a block at the exact same time.

  2. A stale block is a block that is not accepted and those transactions have to return to the mempool.

  3. Stale blocks occur when the blocks from one miner are rejected from the network after two miners solve a block at the same time. The other miners block becomes the true continuance of the network.

  4. Because you don’t want to take a chance that your transaction is going to be on a stale block. This isn’t always the case but it’s good to be mindful of what can happen especially with the fact that two miners can solve a block at the same time.

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#4061

1. What happens in the bitcoin network when two miners solve a block at the same time?
The block with the most proof of work will be accepted and the other one will be dropped.

2. What is a stale block?
A stale block is a valid block that has been rejected from the network due to the higher amount of PoW from the competing block.

3. How do stale blocks occur?
When two miners start to mine blocks at similar times.

4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
Because of the stale blocks, at some point in time, there can be two versions of the blockchain. In order to have only one version of the blockchain, nodes need to wait for the accepted block. Afterwhich all the nodes will accept it as truth and update their version of the blockchain accordingly.

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#4062

1.) Only one block will make it in the end, and that is dependent on which block the next miner chooses to add onto.

2.) A stale block is a block that has been removed because more than one block was added at the same time. The transactions from the stale block are then sent back to the mempool.

3.) Stale blocks occur when more than one miner comes up with a valid block, but there can only be one version of the blockchain so a stale block is one that has been discarded.

4.) It is important to wait because it is possible that your transaction ended up in a stale block and has not yet made it onto the blockchain.

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#4063
  • 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?
    Dropped blocks are called stale blocks also called Orphaned blocks
  • How do stale blocks occur?
    Its the block with the shorthest chain that gets dropped
  • Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
  1. It is important to wait for 6 confirmations to be sure that the block your transactions are in is not dropped from the chain.
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#4064
  1. The chain splits into two ends. both valid!
  2. block that was dropped from the blockchain due to an occurrence of a fork, and not being the block that the chain continued on.
  3. They occur when two miners mine a block at the same time, both valid
  4. once one chain is accepted as the main chain, the transactions of the loosing chain are returned back to the mempool. this is a stale or orphan block
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#4065

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    –> this creates a temporary fork in the blockchain whereby the longer chain ends up being the one propagated.

  2. What is a stale block?
    –> a dropped block that was previously accepted in a fork but didn’t become the longer chain.

  3. How do stale blocks occur?
    –> by not being part of the widely adapted/longer chain they get dropped by majority consensus

  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    –> because 2 blocks may be temporarily accepted at the same time. The longer fork will be determined within 6 blocks

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#4066

Nodes don’t wait for anything, they accept the first block they received or the one with more PoW. The reason why the user should wait when sending/receiving a tx is to make sure his tx doesn’t end up in a stale block. :slight_smile:

#4067

the blocks will be accepted but only the longest chain of blocks will be confirmed (only certain after 6 other block confirmations herafter)

A stale block is a block that has been dropped because another block had the longest chain (most proof of work)

when two blocks have been created, accepted BUT not confirmed.
The one that gets confirmed will be able to continue to exist; the other one doesn’t and is called Stale Block

Only when 6 other confirmations (blocks) have been connected
it will be accepted unto the blockchain
(otherwise there is still a chance another chain of blocks continues the chain

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#4068
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    ans-there will be two new blocks being added to the block chain temporarily.
  2. What is a stale block?
    ans-it is a block that has been removed from the block chain by consensus as it isn’t part of the longest blockchain.(a block that isn’t confirmed)
  3. How do stale blocks occur?
    ans-they occur when blocks are being added to the blockchain too quickly. they would result on a temporary fork on the block chain.
  4. Why is it important to wait for more than one block to be confirmed when sending or receiving a transaction?
    ans- because there is a slight chance of that block being a stale block and the transactions list on that specific block being sent back to the mempool.
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#4069

  1. What happens in the bitcoin network when two miners solve a block at the same time?
    The block chain will fork with 2 different blocks, the next miner will add their block to one of the 2 forked blocks forming a longer chain, this will be sent to the network and verified. The other block will be dropped and the transactions returned to the mempool.

  2. What is a stale block?
    A dropped block

  3. How do stale blocks occur?
    When more than one block is added to the chain at the same time, blocks that aren’t confirmed are dropped from the blockchain

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

To be sure that the block and therefore transaction will be dropped from the block chain.

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#4070

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

Temporarily there will be two true versions of the blockchain. But once the next block is added to the chain one of the duplicates will be orphaned. Since the newest block is based on one of the two older versions the blockchain will favor the longest chain and keep that version.

2. What is a stale block?

A block that has been rejected from the chain.

How do stale blocks occur?

When the chain forks temporarily and one of the new blocks must be discarded back to the meempool.

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

Because this will be enough time for the whole blockchain to aknowledge the blockchain as truth.

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#4071

1.The block will begin to sych to the nodes closest to those two miners, which ever block gets added onto with another block and becomes longer will be the one that remains and is the truth for all nodes.
2. A stale block is one that was dropped after being confirmed
3. Stale blocks occur when a block has the correct nonce but a different block had a new block added on to it first and becomes the valid blockchain.
4. Because your block could be a stale block, there needs to be at least 6 new blocks after your block to know that you are the valid blockchain.

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#4072
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    if 2 miners reach the same target at the same time then the nodes closest will be propagating the blocks. They have to wait until another miner comes and joins one of the blocks. The orphaned block will be ignored. The winner will be the one with the longest blockchain.
  2. What is a stale block?
    A stale block is a block that was once in the blockchain but then got dropped because there is a version of the blockchain that is longer without it.
  3. How do stale blocks occur?
    If blockchains are becoming longer without it
  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 6 more blocks to add on to your block. This is also important with the 10 minute rule.
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#4073

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

The nodes closest to the miner receive the block. There then is two different blockchains in existence. Bitcoin network wants the most pow.

What is a stale block?

Blocks that were once on the blockchain, then removed.

How do stale blocks occur?

Bitcoin network has two miners solve a block at the same time. One of the blocks is confirmed and the other is dropped, even though it was valid.

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

So that one can be sure that the block is confirmed and stays on the blockchain.

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