1) What is blockchain, and why is it innovative?
Blockchain is an absolutely new, decentralized, safe, and transparent solution that allows the storage and exchange of information, determination of its authenticity, and a low price. In this technology, everything is done by the user, so the transaction does not require the participation of a third trustee. It is the absence of an intermediary that is the main innovation and originality of the distributed ledger. The most famous application of blockchain technology is digital currency: crypto assets or digital money like Bitcoin, Ethereum, Ripple, etc. This technology can also be used in many other areas.
2) How does the blockchain work?
To create and work on the blockchain, one needs a registry (a row of blocks, for example, Bitcoin), encryption with keys to protect the transaction, a consensus algorithm for verifying transactions, and a peer-to-peer network to make everything work. Add participants, and you will have all the necessary elements.
Preparing the blockchain developer interview questions, don’t forget about various tasks. To see the technical skills of the candidate, you can ask him or her to create, for instance, a simple blockchain model.
3) How does blockchain differ from traditional databases such as RDBMS?
The most significant difference between blockchain and the traditional database is centralization. Traditional databases are centralized in nature and hence provides a limited trust, integrity, and transparency to the network. The following table gives a better understanding of their difference.
| Criteria | Blockchain | Traditional Database |
| Nature | Centralized | Decentralized |
| Basic Unit of Data | Block | Table |
| Immutability | Yes | No |
| Trust | 100% | Partial |
| Failure | None | Can happen |
| Transparency | Completely transparent | Not completely transparent |
| Operation | Read and Write | Create, Read, Update and Delete(CRUD) |
4) What are the main blockchain features?
Blockchain has a lot of features. The main features are as below.
- Security: Blockchain provides unparalleled security
- Immutability: Data once are written cannot be changed or altered.
- Fast: Blockchain offers quick transactions
- Decentralized: Any centralized authority or entity do not control it
- Fault-tolerant: Blockchain networks are fault-tolerant.
- Low transaction fees: No need for the third party makes it cheaper and more effective
- Minting: Provides coin minting by various methods.
5) What are the main advantages of blockchain? Is there a single type of blockchain?
The biggest advantage of blockchain which has made it so popular is its ability to enable information to be distributed without letting the users copy it.
No, there are three types of blockchain; Public, Consortium, and Private.
6) List the key features of blockchain?
The four main key features of blockchain are:
- Decentralized Systems
- Safer & Secure Ecosystem
- Distributed Ledger
- Minting
7) What is the difference between cryptocurrencies and Blockchain?
The Blockchain is the underlying technology whereas cryptocurrencies are the application of this technology to specific business problems.
The 2 are often conflated because Blockchain was first used in the context of Bitcoin. We can say that Bitcoin is a cryptocurrency (digital money) that is powered by the Blockchain technology.
For Bitcoin, the Blockchain technology is used to maintain a ledger of who owns which quantity of Bitcoin, but it doesn’t need to be that way For example, Steemit is a blogging platform that leverage the Blockchain to store articles and protect them against any form of censorship.
8) What is a Merkle tree?
Merkle Trees are data structures that are used extensively in Blockchains.
Before describing the structures of a Merkle tree, let’s first understand what they are used for.
What are the different types of Blockchains?
The different types of blockchains which introduce to the world are:
There are mainly three types of Blockchains introduced to the world.
1. Public Blockchain
A Public blockchain is a kind of blockchain which is “for the people, by the people, and of the people.” There is no in-charge it means anyone can read, write, and audit the blockchain. It is an open-source, distributed, and decentralizes public ledger so anyone can review anything on a public blockchain. They are considered to be Permissionless blockchain.
2. Private Blockchain
A Private blockchain is a private property of an individual or an organization. It is controlled by a single organization that determines who can read it, submit the transaction to it, and who can participate in the consensus process. They are considered to be permissioned blockchain.
3. Consortium Blockchain or Federated Blockchain
In this blockchain, the consensus process is controlled by a pre-selected group, i.e., group of companies or representative individuals. These pre-selected group is coming together and making decisions for the best benefit of the whole network. Such groups are also called consortiums or a federation that’s why the name consortium or federated blockchain.
Every block of Blockchain consist of what elements?
Every block must include these three things:
- A hash pointer to the previous block
- Timestamp
- List of transactions
9) What is a ledger? Name the common type of ledgers that can be considered by users in Blockchain?
A ledger is a file that is constantly growing. It keeps a permanent record of all the transactions that have taken place between two parties on the blockchain network.
There are three common types of a ledger that can be considered by users in the blockchain:
- Centralized Network
- Decentralized Network
- Distributed Network
10) What makes block unique?
Each block has its own has a value attached to it. They can be identified with the help of block height and block header hash value.
11) Why is blockchain more trustworthy?
The blockchain is trustworthy because of many reasons. The first reason is the security that blockchain offers. It is the most secure technology solution right now. Next, it is entirely decentralized. This removes the need for a centralized entity and the risks associated with it.
The last feature that makes blockchain more trustworthy is immutability. Data once stored cannot be changed.
12) What is Node Application? Explain in detail
Node application is a computer application that a computer needs to be part of the ecosystem. Without the node application, it is not possible for a device to participate in blockchain activity.
There are different node application when it comes to the blockchain. Bitcoin, for example, uses the Bitcoin wallet application to make a computer compatible with the blockchain.
Technically, there is a service overlay network(SON) that interfaces between the blockchain and the computer. The computer needs to use the node application to read and reply in a specific manner,
Not all node application is free from restriction. Some blockchains are stick when allowing a node to join the application. It needs permission to do so.
13) Is RSA a secure algorithm?
Yes, RSA is a very secure algorithm. But there are different ways that this algorithm is attacked. It may be attacked by brute force, and occasionally attacked mathematically.
14) What are the perils of information leak to an organisation?
Not only can a piece of information bring a company into crisis due to reputation harm, but it can also bring about financial losses to an organization too. The lost trust of customers affected may result in a depletion of repeat business.
15) When a distributed digital ledger records a transaction in Blockchain. In this instance, what does the system rely on?
Network Servicing Protocol & Nodes of Network are there to be relied on in such an instance.
