Homework on Consensus - Questions

Blockchain and Bitcoin 101
#542
  1. If the networks agrees with the transaction then the transaction gets added to the database or ledger. Thus the Consensus was passed and approved.
  2. A centralized database can be altered and is not verified by a consensus. Therefore the truth is skewed.
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#543
  1. It basically means that an opinion or position is reached by a group as a whole.
    2.Central database of a company or an organisation is totally controlled by them. They say what they want and you have to trust them alone, no one else is backing up their claim.
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#544
  1. Consensus helps determining the truth by eliminating the need to trust the other parties to system. Anyone can VERIFY what has happened with no need to TRUST the other parties. All parties have INCENTIVES to behave correctly otherwise none would be interested in building consensus.
    2.In a central database, the single node/authority or the very few nodes/authorities controlling the system are able to corrupt the information stored. In a decentralized database, such as a blockchain, all the nodes keep record of the same information preveting anybody with malicious intentions from corrupting the information stored.
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#545

CONCENSUS

  • What does it mean when we say that in blockchain, consensus determine the truth? - An incentivized network of computers make sure that every transaction is valid
  • How is this different from how truth is determined in a central database? -Central databases are usually owned by a few collaborators who can manipulate the system at any time without proof of work. There is no incentive to be truthful, you could say there is more of an Incentive to not be fully truthful based on potential returns investment.
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#546

  1. What does it mean when we say that in blockchain, consensus determine the truth?
    It means that for each transaction, there are multiple “witnesses” within the network that agree on the exact same thing, and that the “testimony” from all of these “witnesses” are etched in stone and become immutable “truth.”

  2. How is this different from how truth is determined in a central database?
    Again, in a traditional central db, the truth can be tampered with or altered by the ultimate authority over that central db without having to inform or care about any other sources.

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#547

In blockchain, consensus determines the truth?
This is non-centralized verification of the established facts about a thing. This removes the need for a solely trusted 3rd party, eliminating the need for trust in a person or group, which are ALWAYS fallible and error prone at some point in their existence.

How is this different from how truth is determined in a central database?
The expression ‘straight from the horses mouth’ comes to mind, i.e. the information gathered that is closest in origin to the subject under investigation is usually the most reliable, but in a centralized database, it is difficult to verify if the information has been altered.

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#548

1.Consensus determines truth because several parties on the blockchain network agree on a transaction based on previous information already in the blockchain, and decide together using math if it is truthful and then gets added to the ledger. If the parties find the transaction to not be truthful, for example if the funds are not really there, then the transaction won’t go through.

  1. It is different from central databases in that in a central database any individual can decide what is “true” without collaboration of confirmation from several parties. The information on a central database can be changed or damaged, changing the veracity of the information in it. In blockchain you can’t change the information that is already engraved in it and can’t be changed.
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#549
  1. What does it mean when we say that in blockchain, consensus determine the truth?
    When the full network agree on services or materials delivered, then the network is in concensus about what is in the yogurt.
  2. How is this different from how truth is determined in a central database?
    Immutability. Trust. 3rd party varifiers can be used as best alternative option. But with blockchain all parties are idealy incentivised to report the truth.
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#550
  1. What does it mean when we say that in blockchain, consensus determine the truth? Consensus is required in a blockchain by ensuring that disparate (distributed) systems have to agree on the validity of a transaction in order for the transaction to become part of the blockchain. The blockchain computers in the network are incentivized to not-allow invalid transactions.
  2. How is this different from how truth is determined in a central database? In a central database, no one other than the owner of the database verifies the truth of each transaction, leaving entities that interact with the owner of the database to “believe the truth” of the data. This results in potential corruption, both electronic and human, of the data. Furthermore, the data is stuck in its own world (operating system/ database language/ API) – it’s own “silo”, making it very difficult to integrate with supplier/ customer systems.
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#551
  • Consensus work in such a way, that by verifying all the information in the network, no one can be left in the darkness or misled…even when someone tries to. And to make it better you get incentivized for saying the truth.
  • Here the truth gets determined by a group of people, you will see what they want you to see.
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#552

  1. consensus is what allows a block to be accepted into the tip of the blockchain, allow means each node considers the block as correct and therefore holding ‘true’ transactions. The true for one node is only the current ‘absolute’ true if it agrees with all other nodes (majority), therefore if a truth is accepted by consensus then it is the current truth.

  2. in a database truth is what is stored as committed in a certain time. If a db admin changes some transaction values or information then truth will be changed. These data changes can not be done so easily in a blockchain.

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#553

In the blockchain an entire network of computers must reach a consensus before a transaction is accepted as “truth”.

In a central database a single computer determines “truth” and can therefore be easily altered.

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#554

  1. What does it mean when we say that in blockchain, consensus determine the truth?
    Every node on the network is incentivized to be truthful, therefore among a large number of nodes, it becomes statistically overwhelmingly likely that the network as a whole is choosing the truth.

  2. How is this different from how truth is determined in a central database?
    In a central database, you must trust the central authority. In a blockchain, it is trustless, or you might say you need only understand the math (that it becomes statistically overwhelmingly likely that the network as a whole is choosing the truth when each node is incentivized to do so).

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#555

The different nodes on the system all agrees about the incoming new data is legit, so it will be valid and added to the blockchain.

The information are going through a centralized structure, so at some point the original data can be alterated.

#556
  1. What does it mean when we say that in blockchain, consensus determine the truth?

Means every transaction is check by all node of the blockchain , this determine the approve or disapprove based on the correlation of information.

  1. How is this different from how truth is determined in a central database?

The difference is on blockchain information is inmutable, true here is verifiable and transparent. On central database trust could be alternated or hackable for any individual.

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#557
  1. What does it mean when we say that in blockchain, consensus determine the truth?

a) It means that there is a community of nodes/computers verifying the data of every (in all copies of database) transaction is correct and that’s achieved by creating economic incentives for the community of nodes to be honest.

  1. How is this different from how truth is determined in a central database?

a) In a central database, the truth is easily manipulated and can’t be trusted. Usually an individual decides what is true or not true and is easily influenced.

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#558

Good question!
You will learn this later in the course. (51%attack) It would be possible but in Bitcoin, the network is so big that this isn’t feasible. smaller blockchain networks using proof of work consesus are more vulnerable to this.

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#559

  1. Any new transaction coming onto the network is checked across many computer held ledgers and only when there is enough verification achieved will we get consensus and the new transaction written to the ledger.

  2. In a centrally managed database the owner or authority for the database would need to manually make the checks before adding new data records to the database. Plenty of scope for error and mis-information!

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#560
  1. What does it mean when we say that in blockchain, consensus determine the truth?

Every participant in the network is incentivised to verify every transaction and when a certain number of nodes verify it, the transaction goes on everyone’s ledger.

  1. How is this different from how truth is determined in a central database?

In a central database whoever has created it, can manipulate it in any way he likes. So no one can really verify it’s authenticity.

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#561

As blockchain is a decentralised network of computers, where there are many individual actors, whom are able to verify the truthfulness of a data input into the network. If the majority of the participants in the network agree, they reach consensus and the data becomes verified.

A central database requires more trust in an individual or a company who created the data, as it is not verified by individual actors in the network.
It is more difficult to audit and verify the data.

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