Homework on Stale Blocks

Blockchain and Bitcoin 101
#1104
  1. The miners propagate their version of the truth to each node. One will not be accepted as truth until another block is added to it that creates the longest chain with the most POW. The other block will be dropped and the transactions will return to the mempool.
  2. A stale block is a perfectly valid block that gets dropped off the chain.
  3. This happens when another version of the blockchain is accepted as the truth over the one it is on.
  4. It creates enough of a chain that you don’t need to worry the block that contains your transaction will become a stale block.
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#1105

  1. Eventually, a third miner will enter the picture and will base his block on one of the first two miners’ blocks. That blockchain, which is the longer one, will be accepted by the network since it has the most proof of work.

  2. A stale block is a block that is dropped by the network due to it being part of a shorter chain that has been rejected by the network.

  3. When the network has two chains to choose from based on two miners solving a block at the same time, it will choose one over the other due to greater length/greater proof of work. The block, that is on the chain not chosen, is discarded by the network and becomes a stale block.

  4. Your transaction could be part of a block that might get dropped. Waiting for multiple new blocks (at least 6 confirmations) ensures your transaction is in a block that hasn’t been dropped.

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#1106
  1. When this happens, it depends on which version of the blockchain(the longer chain) will the next miner pick up.
  2. Stale block is a completely valid block which has been dropped, because it appear in the same time with other block, but didn’t exist in the version which was picked by the next miner
  3. Stale block occur when they are dropped and not included in the blockchain
  4. It is important to wait for at least several confirmations, because there is a possibility that the block including your transaction is not picked up and becomes stale
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#1107

  1. In the Bitcoin network when two miners solve a block at the same time there are briefly two versions of truth until the longest chain wins and is propagated.

  2. A stale block is a valid block discarded from the blockchain because it was not a part of the longest chain in the network.

  3. Stale blocks occur when valid blocks are a version of the truth that is not accepted by the network because it was not part of the longest chain.

  4. Your transaction might be in a stale block and dropped from the blockchain.

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#1108

  1. The blockchain splits in two valid versions.

  2. Stale block is a block that was valid in the blockchain but was later dropped.

  3. Stale block occur after the another longer chain was accepted and the other version was dropped. Stale blocks are in the dropped one.

  4. Because the new block has to be spread throw the whole world it is much more sure for that after 6 blocks it will be kept in the chain.

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#1109
  1. There will always be 1 version of the truth. So it will all depend on the next miner. Whatever block the next miner chooses will be the confirmed block. The target will be lower in this case and therefore the difficulty will be higher.
  2. A stale block is the block that has been dumped, the block that was previously in the blockchain but not confirmed.
  3. Stale blocks occur because nodes accept the block closest to it first or faster. they validate it while the other nodes are busy validating the other block closest to it. In other words 2 blocks are validated by different nodes at the same time.
  4. Its important to wait for more than one block to ensure that particular block doesnt get dumped.
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#1110

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

What i see happening is, that the network must then decide who’s block/version of the truth is more truthful. To do that, the network sees which chain has more proof of work on it, it doesn’t matter which is longer, its which one has more work put into it, and that chain continues to have blocks built on it.

What is a stale block?

What I’ve come to understand is that a stale block is a block abandoned off the main chain because it didn’t meet the requirements for it to continue, usually not enough proof of work on the chain so its not a long enough chain. The chain with the highest difficulty is the one chosen, gotta keep it immutable.

How do stale blocks occur?

What I’ve come to understand is when to competing miners come to the same or similar conclusion at the same or about the same time, only one can be chosen, usually this confusion comes into play when miners who are farther away from each other are on slightly different parts of the same page so only can be chosen to get them back on the same part of the page.

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

The conclusion I’ve come to as to why its important for more than one block to be confirmed when sending or receiving transactions is because there’s still a possibility that your block or chain could be dropped and be on a stale chain, usually after 6 confirmations, you know almost definitively that your transaction as made it onto the blockchain.

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#1111

Correct. However, when 2 miners find a block at the same time we have a temporary fork in the blockchain. We have 2 versions of truth. :smiley:

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#1112

Exactly. This will cause a temporary chain split.

Not at that exact point. But rather after one blockchain gets longer than the other one. :smiley:

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#1113

Not exactly. When 2 blocks are mined at the same time, you still aren’t sure which one is the stale one. Its not until one of the chains gets longer that you can say with certain which block is the stale block. :slight_smile:

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#1114

Exactly. It is a temporary split which will most likely be resolved in a next few blocks.

No. And they can’t sell them either as the newly generated coins are locked for 100 blocks.

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#1115

Yes. And the blockchain that gets the new block faster will be the real truth. The last block from the other chain will become stale. :smiley:

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#1116

What about the last question?

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

If you need any help feel free to message me back.I can always help you. :smiley:

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#1117

Exactly. It is very unlikely that we would have 2 mined blocks at the same time, 6 times in a row. :smiley:

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#1118

Uuuuu, nice observation. I never actually realized this. Thank you so much for bringing this up. You kinda blew my mind with this. But since the blockchain will be resolved in the next block, it will still only take roughly 10 minutes to find a new block. :heart: :heart:

Yes. But the actual stale block happens when the shorter chain gets dropped.

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#1119

It matters. A longer blockchain = more proof of work.

There is no main chain when two blocks are solved at the same time. There are 2 versions of truth. A stale block is a block that was once valid, but is no longer part of the blockchain.

Following up from the last question. Since one of the chains will eventually get a new block, the one that does not get it will have its last block be a stale block.

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#1120

  1. When two miners solve a block at the same time and, hence, are propagating their block through the network, you now have two competing chains instead of one. Nodes closest to Miner1 & Miner2 will receive different versions of the recently appended block on the chain until the next block is mined, so that half of the network has one version of truth propagating that is different from other half. Although both blocks are completely valid with nonces below the target, Miner1 may not have identical TXs as Miner2 in their block. Nodes in blockchain1 will not know and/or may not have heard of blockchain2 when asked. But once a new block is mined, whichever chain the next Miner appends its block on (one of two chains) will be longer and accepted as true by the network since it has the most proof of work. Shorter blockchain will be discarded and all TXs therein will be invalidated and returned to the mempool until it is mined again.

  2. Stale or Orphaned Blocks are blocks that were completely valid blocks in the chain at one point but then got dropped because there’s another version of the blockchain that’s longer.

  3. Stale blocks occur when two miners solve and append a different block on the chain at the exact same time, or two blocks on two chains are competing with each other. But there should only be one version of truth, i.e. the longer chain with the most proof of work such that blocks appended on the shorter chain following the fork will have to be dropped and moved to mempool.

  4. It is important to wait for more than one block to be confirmed when sending or receiving a transaction to be sure your block does not get dropped or become stale. The Best Practice is to wait for 6 confirmations. In a situation where lots of blocks are mined all the time, the network may not always be able to synchronize fast enough since info needs to travel physically and occurring globally. Thus, to avoid having some nodes with different blocks, which leads to dropping blocks, you’ll be on the safer side to wait and be sure everyone has received and validated a new block, and are ready for the next block.

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#1121
  • When two miners solve a block at the same time, they both start propagating their block to the nodes around them. At this time, there will be two different chains competing.
  • A stale block is one that was valid (solved by a miner with a good nonce) but later dropped because another miner’s block was used to create a longer chain.
  • Stale blocks occur when two miners solve the puzzle at the same time creating two competing versions of the blockchain that are being spread through the network at the same time.
  • Waiting for more than one confirmation ensures that a transaction won’t be returned to the mempool in an orphan block, and by waiting, it prevents double spending.
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#1122
  1. What happens in the bitcoin network when two miners solve a block at the same time?
    Both blocks are appended to the blochain in different locations.
  2. What is a stale block?
    A stale block is a block that gets dropped from the blockchain because the other version of the blockchain became the consensus truth.
  3. How do stale blocks occur?
    When 2 blocks are appended to the blockchain at the same time, there are two versions of the block chain. Once one of them emerges as the consensus, the other blocks are dropped and the pending transactions go 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?
    A block can be confirmed by several miners before a block is dropped. In which case your transaction is no longer confirmed.
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#1123
  • In this case the network waits until another miner produces a block and appends it to the blockchain.
  • If this block is appended to the blockchain of one of the blocks that were produced at the same time, then this block will remain part of the blockchain and the other block will be dropped from the blockchain and it’s transactions will be returned to the Mempool.
  • A stale block is a block that has been dropped from the blockchain
  • Stale blocks occur because their part of the blockchain becomes shorter than other parts of the blockchain
  • The network will always choose the longest blockchain, so the block that is part of the shorter blockchain will be dropped (become stale/orphaned) even though it was produced at approximately the same time as the other block
  • This is important in order to ensure that the produced block and it’s transactions are still part of the blockchain after a number of other blocks have been appended to the blockchain, and that the block has not been dropped.
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