I implemented a PoA network as per this example, and it states:

If N sealers are defined in the genesis file, clique will only work if int(N/2+1) (source code) nodes are online. This means that if we define 5 sealers in the genesis file, we will need a minimum of 3 nodes to be mining (sealing) for the blockchain to work. If we define 4 sealers we’ll also need at least 3 mining nodes.

I am wanting test how many bootnodes are needed. I had assumed we should keep the number of bootnodes to a minimum. But should there be one bootnode per server (ie instance in the cloud)?

  • your question title refers to bootnodes but the text you've quoted is referring to sealers - do you mean to ask how many sealing nodes you need? In a private network you don't need any bootnodes necessarily - we simply provide the enode address of some existing nodes on our network and let the P2P discovery happen from there
    – TC8
    Apr 16, 2018 at 8:06
  • I guess I was thinking in terms of bootnodes related to sealers. I am a little unclear on the difference between a signer, a sealer, a miner, a voter, and a bootnode. So I was trying to establish how these terms are related and implemented. I have been getting numerous errors with proposals under clique and I want to understand more about the structure under PoA. Apr 17, 2018 at 6:24

1 Answer 1


This depends entirely on how failsafe you want the network to be and how good the uptime of your infrastructure is. For example, Ethereum mainnet has 6 bootnodes, geographically distributed, Ropsten has 4, Rinkeby has 3.

The number of bootnodes is not related to the number of sealers.

As far as Ethereum/Clique terminology goes:

  • Signer: The account that was used to signed a transaction. The private key is used to sign.
  • Sealer: A node that can sign blocks. Synonymous to authority node.
  • Miner: Same thing as sealer or authority node.
  • Voter: A node that can vote other authorities in or out. In Clique, it must be an authority node/miner/sealer.
  • Bootnode: A node that is used to bootstrap the P2P network discovery. May be a dedicated bootnode (see the bootnode executable) or a normal node (authority or not). Must have a static IP address and a known nodekey, so that you can create the enode URL and pass it as --bootnodes argument to the other nodes.

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