Blockchain Interview Questions — Bitcoin
- How many total Bitcoins are out there ?
Answer: everyone knows that -> 21 million: maximum number of bitcoins that will ever exist
2. What do bitcoin miners do ?
Answer: an open questions where you should get the general knowledge
3. How much does it costs nowadays to send 1 BTC ? but 100 BTC ?
Answer:if it’s ~$1 then the answer is correct
4. What is a confirmation ? How many do you need ?
Answer:see: https://www.buybitcoinworldwide.com/confirmations/
5. Give examples of few bitcoin wallets
there are many…
6. What is the safest way to keep your bitcoins ?
if the answer includes: cold storage, bonus. If it includes multisigs, big bonus
Intermediate Level
- What’s the size of a full bitcoin node nowadays ? What’s the reason to hold a node ?
~ 230 GB
2. What are BIPs ?
Bitcoin Improvement Proposal (BIP) is a design document for introducing features or information to Bitcoin. The BIP should provide a concise technical specification of the attribute and a rationale for the feature. This is the standard way of communicating ideas since Bitcoin has no formal structure.
3. What are change outputs ?
Change outputs are regular outputs which spend the surplus satoshis from the UTXOsback to the spender. They can reuse the same P2PKH pubkey hash or P2SH script hashas was used in the UTXO, but for the reasons described in the next subsection, it is highly recommended that change outputs be sent to a new P2PKH or P2SH address.
4. What’s the best programming language to interact with bitcoin blockchain ?
The correct answer is: none, all are good.
Advanced Level
- Explain Segwit
2. How would you do double-spending in Bitcoin ?
3. What’s the most reliable source to get accurate bitcoin pricing data ?
an experienced developer should know other things regarding bitcoin, not just programming.
if he sais “coinmarketcap” then it’s a minus
4. What’s the purpose of Locktime in a transaction ?
- If less than 500 million, locktime is parsed as a block height. The transaction can be added to any block which has this height or higher.
- If greater than or equal to 500 million, locktime is parsed using the Unix epoch timeformat (the number of seconds elapsed since 1970–01–01T00:00 UTC — currently over 1.395 billion). The transaction can be added to any block whose block time is greater than the locktime.
4. What are BIP44, BIP49 and BIP84 ?
A nice explanation is here:
5. What are the standard pubkey script types ?
- Pay To Public Key Hash (P2PKH)
- Pay To Script Hash (P2SH)
- Multisig
- Pubkey
- Null Data
6. Why blockchain.com is a shitty wallet ?
an experienced developer should follow what’s trending online, not just code.
there are many reasons including stalling of segwit for a long time, improper automatic calculation of tx fees, constant pop-ups to provide your photos IDs, lying in the XLM airdrop
