There are answers related to the number of confirmations is considered secure in Ethereum.

@Waqar Lim

To sum up, it always depends on your application and the attached value to consider which number of confirmations is considered to be secure.

How is it considered for Ethereum PoA network? Do we need to wait for 6 blocks confirmations considered to be secure for Ethereum PoA network?

Is there any possibility to have a fork?

3 Answers 3


I guess that depends on your network layout and your level of trust. If it's a big and distributed network there is bound to be some latency and you will get sub-chains. But if it's small and trusted you will get a lot less sub-chains. I guess PoA chains are typically quite small (maybe?).

The amount of confirmations you want to wait for is up to you. In the Ethereum mainnet some exchanges require 10 confirmation. In a much smaller network the amount should probably be lower, but it's all up to you. The more confirmations you wait for the more secure the transaction is.


In addition to the above, it depends on which flavour of PoA you are running.

Clique has determinstic finality and is works off GHOST (Greediest Observed Heavy Subtree). So depending on your trust model, you might want to wait a couple of confirmations.

Aura on the other hands provides finality after a majority vote i.e greater than n/2 validators have voted on the block, so ideally it would depend on the number of validators and your stepDuration


  • How is it handle on Rinkeby, which is large network? @Samuel Dare
    – alper
    Commented Jul 29, 2019 at 21:21
  • Although my answer naively assumed a private chain, Rinkeby is a proof of authority testnet based on Clique (EIP Here: github.com/ethereum/EIPs/issues/225). So you are implictly trusting the validators already and shouldnt have to worry too much about validators on Rinkeby acting malicious ; there are not incentives and the validators are trusted
    – 0xsegfault
    Commented Jul 29, 2019 at 21:27
  • 1
    Since the validators are trusted; I think 0 block confirmation should be reasonable. I think that could be the case on the private PoA created by Clique as well since the validators are selected via voting and should be trusted as well in my opinion. @Samuel Dare
    – alper
    Commented Jul 29, 2019 at 21:32
  • 1
    EoS is another kettle of fish and I am neither qualified nor have any desire to comment on . PoS_DAO uses a variant of Aura so its finality rules more or less apply there. They are also rapidly working on Honey Badger which i think is a far superior algo. The confirmation blocks number is based on how reversible transactions are in the consensus algorithms. In aura once you have greater than n/2 validators signed , the block is finalised so number of confirmations is related to the number of validators.. not neccesarily block confirmation rounds
    – 0xsegfault
    Commented Jul 29, 2019 at 21:50
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    check out this paper for my rational behind clique : ceur-ws.org/Vol-2058/paper-06.pdf
    – 0xsegfault
    Commented Jul 29, 2019 at 22:05

Who can join this PoA network? Do you trust them all 100%?

If so, you do not need to wait for 6 confirmations.

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