ethash

A: In DAPP, there is no central server to coordinate the nodes or to decide what is right and what is wrong, so it is really not easy to cope with this challenge, and the consistency protocol (concensus protocol) can be used to solve this problem.

Add: *** The core of the knowledge algorithm is to solve the Byzantine general problem (distributed network consistency problem).

A: It's hard to fix bugs or update the DAPP.

If I need to grab data from a centralized application, such as vehicle violation information, how can I ensure that the grabbed data is real and valid?

A: In order to access the centralized API, you can use the Oraclize service can be used as a middleman, Oraclize provides TLSNotary validation for the data grabbed from the centralized service smart contract.

While the owner of a centralized app needs to make a profit to keep the app running in the long run, DAPPs don't have owners, but like centralized apps, DAPP nodes need hardware and network resources to keep them running. the DAPP nodes need something useful in return to keep them running, and so internal currencies come into play. Most DAPPs have built-in internal currencies, or arguably the most successful DAPPs have built-in internal currencies. Such as ethereum

Authorized DAPPs are not available to everyone. Authorized DAPPs inherit all the attributes of permissionless DAPPs, but require permissions to participate in the network. Authorized DAPPs have a different ****-aware protocol than permission-free DAPPs. Authorized DAPPs do not have an internal currency.

The Hyperledger project is dedicated to developing the technology to create authorized DAPPs.

Why have a handful of countries decided that Bitcoin is illegal, and the majority of countries haven't made a decision about it? Here's why:

The InterPlanetary File System is a decentralized file system.

The goal is that by making transactions almost instantaneous and hiding information about the transaction account, it also prevents others from tracking the owner with an ISP.

Anyone can be a miner in the ethereum network. Each miner solves the problem alone, and the first miner to solve the problem is the winner, which is rewarded with 5 Ether and a transaction fee for all the transactions in that block. There is no limit to how many blocks there are in the blockchain, nor is there a limit to the total number of Ether coins that can be generated.

Any node in the network can check that the blockchain is legitimate, first by checking that the transactions are legitimate in the blockchain and how well the timestamps are verified, and then by checking that the block's target value and random number are legitimate, that the miner is getting a legitimate return, and so on.

How does a node discover other nodes in the network?

The node discovery protocol of Ethernet: Kadelima, in which there is a special node Bootstrap node. It keeps a list of all nodes connected to it over a period of time, but it does not keep the blockchain itself.

When peer nodes connect to the Ethernet network, they first connect to the Bootstrap node.

There can be multiple Ether instances, which means that the different networks each have their own network ID.

The two main Ether networks are the main network and the test network. Ether is traded on the main network, while the test network is available for developers to test.

A decentralized communication protocol that supports broadcasts, user-to-user, encrypted messages, and more, but is not used to transfer big data.

A decentralized file system.

geth provides a JSON-RPC API for other applications to communicate with it. use HTTP, WebSocket, and other protocols to serve the JSON-RPC API.

The APIs provided by the JSON-RPC API are grouped into the following types:

Nodes in the EtherChannel network are by default served with 30303 port to communicate.

--networkid is used to specify a network ID, with 1 being the main network ID and defaulting to 1, and 2 being the test network ID

--dev marks a private network as running

--etherbase specifies the wallet address where returns earned from mining are deposited

--unlock unlocks one or multiple accounts

The etherbase wallet is bundled with geth. When running Ethernet, it tries to discover a local geth instance and connect to it; if it cannot discover that geth is running, it starts its own geth node. Etherwallet uses IPC to communicate with geth. geth supports file-based IPC.

The name of the next major update to Etherwallet. serenity has changed the *** knowledge protocol to casper, and will be integrating state channels and sharding.

Casper implements a process that makes it possible to penalize all malicious elements. This is how proof of equity works under Casper:

Verifiers stake a percentage of the Ether they own as a deposit. Then, they will start verifying blocks. That is, when they find a block that they think can be added to the chain, they will verify it by placing a bet.

If the block is added to the chain, the verifiers are then rewarded with a sum proportional to their wager. However, if a verifier acts in a malicious manner and tries to do something "disinterested", they are immediately penalized and all their equity is cut off. As you can see, Casper is designed to work on a system that doesn't need to be trusted, and is more Byzantine in its fault tolerance.

The Payment Channel feature allows for more than two transactions that send Ether to another account to be combined into two transactions. It works as follows: let's say X is a video site owner and Y is a user. x charges 1 Ether per minute. Now X wants Y to pay every minute while he watches a video. Of course, Y could broadcast the transaction every minute, but there are some problems here, such as X having to wait for a confirmation, so the video is interrupted for a while. The payment channel solves this problem. Using the payment channel, Y can broadcast a locked transaction that locks some Ether (say 100 Ether) for X for a period of time (say 24 hours). Now for every minute of video, Y will send a signature record indicating that it can be unlocked, and one Ether goes into X's account and the rest into Y's account. After another minute, Y will send a signature record indicating that it can be unlocked, and two Ether coins will go into X's account and the rest into Y's. The process will continue while Y watches videos on X's website. Now let's say Y has watched 100 hours of videos or the 24 hours are up, X will broadcast the last signature record to the network in order to receive the money into his account. If X doesn't withdraw the money within 24 hours, the full amount will be returned to Y. So in the blockchain, we will see both lock and unlock transactions.

Sybil Attack

51% Attack

Supplement: cannot store larger data, currently there are distributed storage options like Swarm & IPFS available

Keeps everything in memory, so once a node is restarted, it will lose its previous state.

Default listening port: 8545