Homework on Consensus - Questions

Blockchain and Bitcoin 101
#21

  1. Consensus determines truth in blockchain because the only valid ledger on a blockchain is the one where the majority of nodes on the network share and broadcast the same information, therefore reaching consensus.

  2. In a central database, truth is determined by those who control it. If there is only one party in control of a central database, they can change the inputs of a database to reflect whatever they consider true. Truth is most likely derived from a central source with the ability and incentive to alter it. In blockchain, truth is derived from numerous distributed sources that, for the most part, cannot be altered and have little incentive to do so.

Feedback is always appreciated if I left something out or made an error.

4 Likes
#22
  1. In order to determine the truth in blockchain architecture, all the computers of the network must achieve an agreement on the data introduced in the network. This agreement, based on logarithmic calculations, is one of the most important features of decentralized blockchain like bitcoin and guarantees that no central authority take any decision, but the consensus of the all community.
  2. In a central database the truth is claimed by a central authority that holds the keys to access to its system and no one is entitled to enter it without authorization. The informations stored in centralized database can be manipulated anytime only by whom holds the keys. Thatā€™s the opposite of whatā€™s happening in decentralized blockchain.
5 Likes
#23

  1. What does it mean when we say that in blockchain, consensus determines the truth?
    All computers will check if transactions send to the blockchain are correct, not double spend, etcā€¦

  2. How is this different from how truth is determined in a central database?
    Not everyone in a network can take a look in each otherā€™s database or excel sheet.

1 Like
#24
  1. What does it mean when we say that in blockchain, consensus determine the truth?

Answer: Each new transaction must be verified by the other computers on the network. Each computer performs an independent, unbiased check of the results. The resulting ā€˜consensusā€™ becomes ā€˜truthā€™ and is stored on the blockchain.

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

Answer: In a central database there is no cost barrier to adding new data to the database. There is also no outside check to make sure that whatever the database is for, it truly represents the quantities it is supposed to.

8 Likes
#25

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

The decision of accept and confirm of transaction always made together and be double checked by the network. The truth will be verified, not be told, so no one can cheat in this case.

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

In a central database is very hard or impossible to verify every single transaction, or source of information from different sides. The truth could be, or usually be one side story. Fake information canā€™t be avoided. The truth in a central database can easily be manipulated.
The special of Consensus is: it builds on incentive. Truth behavior makes reward. There is no such mechanism in a central database.

1 Like
#26
  1. Consensus is done through a network of computers which validates each transaction.
  2. In central database truth is controlled by a central authority which is prone to cheating unlike in consensus
2 Likes
#27

  1. Here Consensus means the consensus among the nodes. It means that the nodes of the Blockchain decides the validity of any transaction being performed. Here they carries out two key functions of Blockchain. First - Allow a blockchain to be updated. Second -By preventing any single-point-of-control that can derail the whole blockchain system.

  2. The major difference is Decentralized Control which eliminates the risks of centralized control. Anybody with sufficient access to a centralized database can destroy or corrupt the data within it. There is no other way than relying on the security infrastructure implemented by the database administrator.
    Blockchain technology uses decentralized data storage to sidestep this issue, thereby building security into its very structure while providing 24*7 HA.

2 Likes
#28

  1. Every node in the network verifies that new data is correct and they are all incentivised to do that accurately.

  2. Usually one node would process the information and add it to the database leaving a single point of failure or corruption, even if there are multiple fail over nodes, only one will likely process it in a centralised system.

2 Likes
#29
  1. What does it mean when we say that in blockchain, consensus determine the truth?

To validate the truth in blockchain multiple decision makers are required and also incentivized in the task.In this way the network prevents fraudulent activity and therefor any changes or accidental loss of information is not possible.

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

In a traditional database an owner can independently corrupt the data therefor any truth can be manipulated / changed at any point in time.

2 Likes
#30

  1. It means that there is a specific mechanism/rules (consensus algorithm) that every node in the network agrees to. This agreement specifies what is true and what is false (e.g. a transaction) and whether to approve something that someone claims in the network or not.

  2. Truth in a central database is determined by whatever the central authority that controls the database claims. In this case the truth is determined from a single centralized entity and not from a network of entities that collaborate between each other.

1 Like
#31

  1. Consensus is blockchains is achieved by following and verfying the state of the network with the same set of rules which are enforced by incentives. Nodes are incentivised to play fair and by the rules which keeps everyone on the same page.

  2. On a central database, thereā€™s only a single entity enforcing rules for the network and hence thereā€™s always consensus.

3 Likes
#32
  1. It mean that in blockchain if you cant verify it, it is not true.
  2. for blockchain the consensus is inserted in code of the blockchain for a centralized database it can easily be modified by the party in control.
1 Like
#33

Ad.1.Consensus determines the truth by others of the network veryfing the transaction.
Ad.2. In blockchain, there is a network of computers communicating with eachother, which makes it impossible to cheat and itā€™s decentralised, so no authorities has a power over it.

#34
  1. What does it mean when we say that in blockchain, consensus determine the truth?

Because there is a copy of the ledger on every node and everybody needs to have the same copy. Everybody on the chain (miners, nodes) have it in their best interest to help the network and receive rewards.

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

Anyone with the right permissions can change things in a database. You need to trust the database administarors.

1 Like
#35

1- it means that the truth is decided and agreed upon collectively by the network of computers.

2- in a central database the truth is determined by a single author. thus you have to trust the central authority unlike in a decentralized database in which you only have to trust the math.

2 Likes
#36

  1. In blockchain, consensus is when all parties agree on a common verified, mathematically proven truth.

  2. On a central database, truth is not verified. On the blockchain truth is verified by consensus, on the distributed ledger.

1 Like
#37

  1. In blockchain, every node in the network takes part in coming to an agreement. They play by the rules because of incentives. The decison is agreed upon collectively by the network of computers.

  2. In a central database, there is no incentive mechanism and all are part of the same unit. So truth needs to be determined by the central database manager and you need to trust them for it. In blockchain database u only have to trust the algorithm.

2 Likes
#38

1. What does it mean when we say that in blockchain, consensus determine the truth?
If participators in the network (nodes/miners/ā€¦) agree that newly presented data in the network is the truth, then you reach consensus and you can assume that it is really is the truth.

2. How is this different from how truth is determined in a central database?
In a central database data can be changed by the central authority, so you never can be sure about how ā€œtrueā€ is that data.

1 Like
#39

  1. In blockchain, what is meant by consensus determining the truth is that the network of nodes are the ones who come to an agreement on a transaction being verified or denied.

  2. In a consensus there is a majority to verify and determine the authenticity of a transaction, but with a central database there is a designated authority where data can be altered and compromised.

1 Like
#40

  1. In the blockchain, the majority decide what is true and what not. If everyone agrees to a transaction, this will be add to the blockchain, because they reach consensus on this transaction. If on the other hand, one party agrees to a transaction an all the others donĀ“t valid it, this transaction wonĀ“t be added.

  2. In a central database, the owner on the database says, what is true and what not. Other parties donĀ“t have any rights, except to accept it or to leave the database. Even if the database is manipulated.

1 Like