How to Interview a Blockchain Developer | Tips for Recruiters

Cryptocurrency seems to take over the whole world. There are probably not people, who wouldn’t know what bitcoin or Blockchain is. Even though, these are very popular notions, some people are not familiar with the depth of them. So, sometimes it might be challenging for many recruiters to interview Blockchain developers, as they can be confused with what questions to ask about blockchain. Here Mobilunity is interviewing one of our dedicated Blockchain developers Yevhen and finds out how to become a professional Blockchain developer and answers the most frequently asked questions on Blockchain technology.hire blockchain developer at Mobilunity

List of Skills Every Blockchain Developer Should Have

  • Generally, at the very least, 2 years professional experience as a software engineer(bonus points if this was gained in fintech).
  • A deep understanding of ledgers, consensus methods, Blockchains, and cryptocurrencies in general. (HyperLedger, etc…)
  • Strong expertise in threat analytics, anomaly detection, and performance management.
  • Strong understanding of algorithms, data structures, cryptography and data security, and decentralized technologies.
  • Strong coding skills with at least one of the following languages: Go, C, C++, JAVA, Python, Solidity (for smart contracts), JavaScript + bigchainDB + web3js
  • A good understanding of distributed storage, like RDBMS or NoSQL, for instance.
  • The usual soft skills like time management, being a team player, and the ability to prioritize tasks.

The required skill-set for other roles like Business Analysts, Researchers, and Marketers who want to work in the Blockchain world would obviously be different.

The biggest thing is just to jump in and get started. Read, learn, try. Rinse and repeat. Good luck!

Top 10 Blockchain Interview Questions and Answers

Blockchain forks can result in which of the following?

Multiple children blocks, for example, we make hard fork which got one improvement. It extends block size to 2MB instead of 1MB. What will happen – node which runs the old version of software will see new transactions as invalid. So if you want to switch to the new node that got block size of 2MB, you need to switch over the chain and continue to mine new blocks.

Is it true of false: A block in the Blockchain can never have multiple children blocks.

False, because all Blockchain consensus protocols have a challenging limitation, every fully participating node needs to process every transaction and needs to make a copy of entire state. That’s why it cannot be added and that’s why there are new forks released.

How many blocks can have Blockchain as parent blocks?

Only 1 block due to Blockchain limitations

Which cryptographic algorithm is used to identify hash of the block in Blockchain?

SHA256 because it gives output in fixed length, 256 bits. This is critical when you deal with huge amount of data and transactions.

How is the first generated block called in Blockchain?

Genesis block – usually hardcoded block in software that utilize it’s Blockchain. This is a special block that does not have any reference to the previous block.

How blocks are linked in the Blockchain?

Backward to the previous block.

What consists in every block of a Blockchain?

  1. A hash pointer to prev block
  2. Timestamp
  3. List of transactions

What data structure is used to summarize all the transactions in a block?

Merkle tree – it’s not verified transactions, it verifies a set of transactions. Transactions ID’s are some kind of hashes of transactions and Merkle tree is constructed from them.

What is considered by miners for adding a transaction to a candidate block?

  1. Transactions fee
  2. Transaction priority

Due to all members of Blockchain use miners nodes to make transaction over Blockchain, miner adds transactions fees. So for example if you want make payment from one Eth address to another you need to pay GAS – and if you pay for example bigger than 10 GAS – for example 100 GAS – your transaction will be putted on high priority level.

What are smart-contracts?

According to Blockgeeks, “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.”

What is the difference between symmetric and asymmetric key encryption?

Symmetric-key: It only needs one key to encrypt the message. And both user only need the same key to decode the message. And the in order to create the key is by moving the bit.

Asymmetric-key: It needs two different keys- public key and private key. Everyone can see the public key and only the person who has private key can decode the message.

Creating the Block With C++ JavaScript

blockchain developer code with C++ JavaScript


Hire Blockchain Developer at Mobilunity

Mobilunity has a very strong team of talented and proficient recruiters, who have years of experience finding, testing and testing any kind of developers for our clients. We are ready to find a reliable team of dedicated developers within 2-3 weeks, depending on the complexity of your project.

Contact us now to get an awesome Blockchain developer for your project!

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