<p>A newbie question. How does block chain distributed system prevent debit beyond account balance? Let us say I have only $100 in my account and tried to do two $100 payments quickly.  If the second payment went to a server in the distributed system that is yet to know about the first transaction, curious how the second payment is handled? </p>

CC BY-SA 3.0
2017-08-24T06:14:10.563Z
Eventually, when the two nodes with the two different transactions come to know about the other transaction, one of the two transactions will be dropped. That is why you should not consider safe those transactions that are in the last block of the chain
Ivano Donadi
CC BY-SA 3.0
2017-08-24T06:23:21.277Z
How long should the receiving party wait to consider the transaction as safe? How does receiving party check to make sure it is safe payment?
frosty
CC BY-SA 3.0
2017-08-24T06:30:02.430Z
It depends on how much security you want. If I recall right it is suggested to wait until the block has six other blocks on top of it to be really really sure it is safe.
Ivano Donadi
CC BY-SA 3.0
2017-08-24T13:51:20.730Z
Watch this, you'll find the answer. https://youtu.be/Lx9zgZCMqXE
MCCCS
<blockchain>
Block chain debit beyond account balance
frosty
# Block chain debit beyond account balance

(Asked by: username_0 on 2017-08-24)

A newbie question. How does block chain distributed system prevent debit beyond account balance? Let us say I have only $100 in my account and tried to do two $100 payments quickly. If the second payment went to a server in the distributed system that is yet to know about the first transaction, curious how the second payment is handled?

**Tags:** blockchain

> **Comments:**
> **username_1**: Eventually, when the two nodes with the two different transactions come to know about the other transaction, one of the two transactions will be dropped. That is why you should not consider safe those transactions that are in the last block of the chain  
> **username_0**: How long should the receiving party wait to consider the transaction as safe? How does receiving party check to make sure it is safe payment?  
> **username_1**: It depends on how much security you want. If I recall right it is suggested to wait until the block has six other blocks on top of it to be really really sure it is safe.  
> **username_2**: Watch this, you'll find the answer. https://youtu.be/Lx9zgZCMqXE  

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