blockchain viva questions with answers
This are some viva question. if you have your own questions please add.
1)what is the process? step by step explanation in your own word.
ans:- please write
2)where is the blockchain used?
ans:- please write
3)what is the use of blockchain in your project?
ans:-
1)to secure transaction
2)maintain integrity:- integrity
A blockchain is designed to be accessed across a peer-to-peer network, each node/peer then
communicates with other nodes for block and transaction exchange
blockchain is a digital ledger.
This ledger exists on the “chain” supported by millions of nodes simultaneously
hacker with access to the terminal will not be able to affect other nodes
4)how security maintained in your project by blockchain.
The concepts of immutability and consensus
Immutability, on the other hand, refers to the ability of blockchains to prevent alteration of transactions that have already been confirmed. Although these transactions are often relating to the transfer of cryptocurrencies, they may also refer to the record of other non-monetary forms of digital data.
While consensus algorithms ensure that the rules of the system are being followed and that all parties involved agree on the current state of the network — immutability guarantees the integrity of data and transaction records after each new block of data is confirmed to be valid.
The role of cryptography in blockchain security
Within blockchains, these output values, known as hashes, are used as unique identifiers for data blocks. The hash of each block is generated in relation to the hash of the previous block, and that is what creates a chain of linked blocks. The block hash is dependent on the data contained within that block, meaning that any change made to the data would require a change to the block hash.
Therefore, the hash of each block is generated based on both the data contained within that block and the hash of the previous block. These hash identifiers play a major role in ensuring blockchain security and immutability.
5)if smart-contract used . how its working?what is smart-contract?
ans:- please write
6)where is data stored?
ans:- please write
7)what is geth?
geth is a tool used to run a full Ethereum node on the system. Suppose you want to access an Ethereum network then you need an ethereum node for that. An Ethereum node is a system that follows the consensus of the Ethereum network.
Geth Ethereum is the command-line interface for implementing an Ethereum node in Google’s Go programming language. Geth serves as a node in the blockchain that helps the user to mine Ether and creates software that runs on Ethereum Virtual Machine. Geth helps to mine real ether, create contracts, make transactions, transfer funds between addresses, etc. Geth is supported on almost all operating systems like Linux, macOS, and Windows.
Geth will connect to the existing live blockchain or create its own, depending on provided settings. Left at the default values, Geth will connect to the live Ethereum blockchain (the Mainnet) which we use daily. Simply by running Geth, you’re already participating in making the Ethereum network better and stronger
8)what is ganache? if used?
Ganache allows you to create a private Ethereum blockchain for you to run tests, execute commands, and inspect state while controlling how the chain operates. It gives you the ability to perform all actions you would on the main chain without the cost. Many developers use this to test their smart contracts during development. It provides convenient tools such as advanced mining controls and a built-in block explorer.
https://www.tutorialspoint.com/ethereum/ethereum_ganache_server_settings.htm
9)what is mining?
its a bitcoin example:-
Bitcoin mining is the process of creating new bitcoin by solving a computational puzzle.
Bitcoin mining is necessary to maintain the ledger of transactions upon which bitcoin is based.
Miners have become very sophisticated over the last several years using complex machinery to speed up mining operations.
10)how security achieved in this project?
ans:- please write
11)what is ether?
Ethereum is a technology that uses blockchain development to replace internet third parties that store data and financial records.
In an idealized ethereum model, no one entity would control your personal data, making it less vulnerable to hacks or shutdowns.
To cover the cost of this power, you likely need to pay a marginal fee — ether is the token by which you make this payment.
A total of 18 million ether are mined each year.
12)which algorithm used by blockchain?
SHA 256 <- 32 bit character
consensus algorithm
We know that Blockchain is a distributed decentralized network that provides immutability, privacy, security, and transparency. There is no central authority present to validate and verify the transactions, yet every transaction in the Blockchain is considered to be completely secured and verified. This is possible only because of the presence of the consensus protocol which is a core part of any Blockchain network.
A consensus algorithm is a procedure through which all the peers of the Blockchain network reach a common agreement about the present state of the distributed ledger. In this way, consensus algorithms achieve reliability in the Blockchain network and establish trust between unknown peers in a distributed computing environment. Essentially, the consensus protocol makes sure that every new block that is added to the Blockchain is the one and only version of the truth that is agreed upon by all the nodes in the Blockchain.
The Blockchain consensus protocol consists of some specific objectives such as coming to an agreement, collaboration, co-operation, equal rights to every node, and mandatory participation of each node in the consensus process. Thus, a consensus algorithm aims at finding a common agreement that is a win for the entire network.
13)what is transaction-receipt?
Transaction receipts
Transaction receipts are used as a mechanism to store the state after a transaction has been executed. In other words, these structures are used to record the outcome of the transaction execution. It is produced after the execution of each transaction. All receipts are stored in an index-keyed trie. The hash (Keccak 256-bit) of the root of this trie is placed in the block header as the receipts root. It is composed of four elements that are described here:
The post-transaction state: This item is a trie structure that holds the state after the transaction has been executed. It is encoded as a byte array.
Gas used: This item represents the total amount of gas used in the block that contains the transaction receipt.
14)where is data stored of users public key?
its stroed in private blockchain E:\privateBlockchain\chaindata\keystore
here all the records private key and data is stored.
15)how blockchain works?
16)is blockchain similar as bitcoin?
17)How its solving real time prooblems?
18)length of blockchain data?
account is of 32 bit
transaction receipt is 64 bit
19)where is server?
We are using tomcat server for connecting android mobile to servlet on port 8080
then servlet on port 8080 connecting to port 8545 of blockchain geth(ethereum) via web3j
20)where data stored?
The user data is stored on blockchain
transaction receipt stored on mysql.. database can be stored anywhere.
21)what is back end?
Back end involves
1)mysql
2)geth/ganache(depends on project)
3)keystore files of private key
22)what is front end?
Android app or
website +android app or
Website
website can be in java servlet or python
Android app is in java
23)how blockchain connected to java application?what is web3
server connect with blockchain using web3j
Web3j is a lightweight, highly modular, reactive, type safe Java and Android library for working with Smart Contracts and integrating with Ethereum blockchains.
This allows you to work with Ethereum blockchains, without the additional overhead of having to write your own integration code for the platform.
24)at which port your blockchain operates?
8545 here we are working we can change this as per requirement or unavailability of port.
25)is blockchain can be hacked?
Blockchain is intrinsically a very secure technology. It’s decentralized nature and cryptographic algorithm make it immune to attack. In fact, hacking a Blockchain is close to impossible. In a world where cyber security has become a key issue for personal, corporate, and national security, Blockchain is a potentially revolutionary technology.
Blockchain technology is, in fact, a group of different technologies that can be used together in different ways to create different end results or applications. It’s open code and can be infinitely customized. While the details will vary between Blockchain protocols, the core of the technology is that it is a decentralized digital ledger of transactions. These transactions are verified in whatever way is deemed appropriate for the particular Blockchain application. This is most commonly achieved by either a ‘proof of work’ or ‘proof of stake’ process.
In order to change the historical transaction history held by the Blockchain ledger, someone wishing to do so would have to somehow reverse engineer the hash of a sealed block. However, making a change would lead to a different hash output once the block was resealed. This new hash would then be out of sync with the ‘stamps’ running through the rest of the chain, alerting the system, which would reject the resealed block.
Once a transaction has already been sealed into a block and added to the Blockchain, changing it is close to impossible. Not only would it be necessary to reverse engineer the hashed block and make a change to the transaction data contained within but this would have to be done simultaneously over at least 51% of the copies of the ledger held on different nodes. This is why it is practically impossible to ‘hack’ a Blockchain
26)how security maintained in blockchain?
A blockchain, as the name implies, is a chain of digital “blocks” that contain records of transactions. Each block is connected to all the blocks before and after it. This makes it difficult to tamper with a single record because a hacker would need to change the block containing that record as well as those linked to it to avoid detection.
27)what is gas limit in blockchain
Gas fees are payments made by users to compensate for the computing energy required to process and validate transactions on the Ethereum blockchain. “Gas limit” refers to the maximum amount of gas (or energy) that you’re willing to spend on a particular transaction. A higher gas limit means that you must do more work to execute a transaction using ether or a smart contract.
28)is our blockchain public or private?
public,private and consortium
https://medium.com/blockchain-strategy-and-use-cases/public-private-and-consortium-blockchains-whats-the-best-flavour-7728834a4b1c#:~:text=A%20private%20or%20a%20consortium,this%20is%20not%20very%20impressive.
our blockchain is private blockchain
29)what is solidity
Solidity is a contract-oriented, high-level programming language for implementing smart contracts. Solidity is highly influenced by C++, Python and JavaScript and has been designed to target the Ethereum Virtual Machine (EVM).
30)what is remix
its an IDE for writing solidity code
31)What are Smart Contracts?
Smart contracts help you exchange money, property, shares, or anything of value in a transparent, conflict-free way while avoiding the services of a middleman.
http://yabit.ru/2018/03/17/what-is-a-smart-contract-auto-enforceable-code/
above some question are project specific not all are related to all projects.
