In a course I'm taking the following question came up:

A 51% attack means:

  A. 51% of the nodes are bots 

  B. 51% of the nodes are hackers
  C. 51% of the nodes are offline or disabled 

  D. 51% of the nodes agree on something

I had answered D, but the correct answer was given as B.

As far as I am aware, I believe that it was required (in a proof of stake system) to acquire 51% of the staked coins. From my understanding, a group of billionaires could get together to acquire said value, and as such, I answered D - 51% of the nodes agree on something, which while is not the way I would choose to answer it if I had the choice, I thought was more accurate than the hacker answer.

I'd think the right information should be: "A 51% attack is when one entity (which may comprise sub-entities) controls 51% of the network's consensus mechanism (be it mining power or value staked), enabling them to manipulate the blockchain." This answer does not contain the term "nodes" nor does it contain the term "hackers".

I tried to talk to the course-coordinator about this and he told me to do more research. The only way for me to do that, due to the specificity of the question, is to ask the opinions of learned people. If there is a better forum for me to post this on, please point me toward it.

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    $\begingroup$ I've removed the fluff of your question so that it may be migrated to a more suitable place, as this isn't about cryptography. I'd agree that the term "hacker" is out of place and that the question / answers are badly formulated; there are plenty of definitions of a 51% attack out there though. Note that you come across as very passive-aggressive and argumentative. For instance, I've removed that part about it not being exactly 51%, but that's just what the attack is called. $\endgroup$
    – Maarten Bodewes
    Jul 12, 2023 at 8:09
  • $\begingroup$ @MaartenBodewes-onstrike thanks for removing the fluff, it wasn't intended to come across as passive aggressive (I guess that is the nature of a passive aggressive post). Which stackexchange forum do you think is the most appropriate to ask a question? Because he told me to do more research and then come back to him. And the only way I can do that is to ask other people their thoughts on the question. I don't recall saying something about the exact percentage? If it came across that way, that was not my point at all, I'll have to read the original. But I wasn't being specific about the %age $\endgroup$ Jul 12, 2023 at 9:08
  • $\begingroup$ @MaartenBodewes-onstrike yes, nothing you removed was about the percentage, it was about whether it was hackers or a general group of people. I just repeatedly used the term 51%, which may have caused the confusion. I realise I typed far too much, as I was in the middle of a course and feeling upset. But for the instructor to shut me down and tell me to do some more research and then come back and talk to him, I think, is relevant. If I am told to do some more research and come back to him, the only way to do that with authority is to ask learned people, due to the specificity of the question. $\endgroup$ Jul 12, 2023 at 9:15
  • $\begingroup$ @MaartenBodewes-onstrike that's why even though there is lots of information about 51% attacks online, and I have read these, the only way that the course coordinator is going to accept my point is if I show him that people who understand this stuff agree with me. Thank you for doing the editing to make it more concise, but I will add a very short point about this. I have a limited time to decide whether or not to withdraw. $\endgroup$ Jul 12, 2023 at 9:16
  • $\begingroup$ As this is not about a particular blockchain I guess it could be asked on Information Security but please first read their help pages. $\endgroup$
    – Maarten Bodewes
    Jul 12, 2023 at 13:42


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