Ethereum: how to find out the last block number
When launching a new Ethereum client or after a period of inactivity, it may take some time for the network to catch up and download new blocks. One of the key indicators of when this happened is the target block number, also known as “target” or “height”. In this article, we will consider how to find out the last block number.
Why do Ethereum clients have to wait?
The Ethereum blockchain consists of a series of blocks, each of which contains new transactions and data. Each block has a unique identifier called a “block hash”, which serves as a reference point for verifying transactions in the network. When a client needs to verify the latest block number, it must download all previous blocks from the blockchain.
This process is called “block verification”. As the client downloads each block, it updates its internal state with the latest information about network activity. The time it takes for the client to check and update this status depends on several factors, including:
- Network speed: a faster connection means that the client can download blocks faster.
- Number of concurrent transactions: A larger number of concurrent transactions increases the time required to verify a block.
- Blockchain complexity: A more complex chain with multiple layers and branches may take longer to verify.
How to find out the last block number
To determine the last block number, you can use one or more of the following methods:
- Check your client’s documentation
: Most Ethereum clients have a built-in help system that provides information on how to check the latest block number.
- Use the
--block-numberoption: When starting the client from the command line, add the--block-numberoption, followed by the value of thetargetfield in the configuration file or client settings. For example:
ethers.js --config path/to/config.json --target=0x1234567890abcdef
This will display the current block number.
- Check the blockchain explorer: A blockchain explorer such as Ethereum Explorer (eg [etherscan.io]( provides information about the last block number, including the
targetfield.
- Use an online tool: There are several online tools that allow you to check the latest Ethereum block number, such as [Ethereum Block Number Calculator](
Conclusion
Knowing the last block number is an important step in understanding how your Ethereum client is performing and whether it is having problems verifying blocks. Using one or more of the above methods, you can determine the current target block number.
Remember that the network is constantly evolving, so even if you recently found the last block number, changes may have occurred since then. Always update your client and regularly check the blockchain browser for updates or network issues.