<p>They don't need to.</p>

<p>If a block's timestamp is in the future, it won't be accepted - but it also won't be marked as invalid. Once enough time passes, the node will accept the block if it is offered or received again.</p>

<p>Effectively, the maximum limit on the timestamp is not a consensus rule, but just a temporary acceptance rule.</p>

CC BY-SA 4.0
2019-03-26T09:49:53.910Z
I had the impression that the nodes ask one another about their UTC timestamps and if it is within 70 minutes of your time, you use that to calculate the median of the network adjusted time.
Ugam Kamat
CC BY-SA 4.0
2019-03-26T06:26:17.553Z
2019-03-26T06:26:17.553Z
Pieter Wuille
<p>From <a href="https://en.bitcoin.it/wiki/Block_timestamp" rel="nofollow noreferrer">bitcoin wiki</a>:</p>

<blockquote>
  <p>A timestamp is accepted as valid if it is greater than the median timestamp of previous 11 blocks, and less than the network-adjusted time + 2 hours. </p>
</blockquote>

<p>If a miner submits a block timestamp on the cusp of the <em>network-adjusted time + 2 hours</em> threshold, some nodes will see the block as valid and some will see the block as invalid, regardless of the work done on the block. How do nodes come to consensus on whether the block is valid?</p>

<consensus><validation><timestamp>
How do nodes come to consensus on whether a timestamp is valid?
wass
# How do nodes come to consensus on whether a timestamp is valid?

(Asked by: username_0 on 2019-03-26)

From [bitcoin wiki](https://en.bitcoin.it/wiki/Block_timestamp):

> A timestamp is accepted as valid if it is greater than the median timestamp of previous 11 blocks, and less than the network-adjusted time + 2 hours.

If a miner submits a block timestamp on the cusp of the *network-adjusted time + 2 hours* threshold, some nodes will see the block as valid and some will see the block as invalid, regardless of the work done on the block. How do nodes come to consensus on whether the block is valid?

**Tags:** consensus, validation, timestamp


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## 1 answers

### Answer by username_1 on 2019-03-26. Score: 5

They don't need to.

If a block's timestamp is in the future, it won't be accepted - but it also won't be marked as invalid. Once enough time passes, the node will accept the block if it is offered or received again.

Effectively, the maximum limit on the timestamp is not a consensus rule, but just a temporary acceptance rule.

> **Comments:**
> **username_2**: I had the impression that the nodes ask one another about their UTC timestamps and if it is within 70 minutes of your time, you use that to calculate the median of the network adjusted time.  

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