<p>Nodes do not need their time to be synchronised. Clocks can be up to two hours different without causing issues.</p>
<p>It is the proof-of-work mechanism, not time synchronisation, that ensures all nodes eventually record all the same transactions in all the same order.</p>
<blockquote>
<p>this would be impossible to do in a huge network tho</p>
</blockquote>
<p>NTP easily syncs nodes to a few tens of milliseconds on a global scale.</p>
<p>Bitcoin doesn't need this.</p>

CC BY-SA 4.0
2024-05-04T09:09:59.817Z
2024-05-04T09:21:23.770Z
2024-05-04T09:21:23.770Z
RedGrittyBrick
<p>Nodes on the Bitcoin network synchronize the network state by processing the blockchain. As they validate each block and apply all transactions to their UTXO set, eventually they catch up to the best chaintip. At this point, they are synchronized with the network and know about all existing pieces of bitcoin. It is not necessary for the node’s local clocks to be synchronized, although if a node’s local time is significantly lagging behind, it may not accept some valid blocks until those blocks timestamp is less than two hours in the future from their local time.</p>

CC BY-SA 4.0
2024-05-06T13:45:35.727Z
2024-05-06T13:45:35.727Z
Murch
<p>From <a href="https://bitcoin.stackexchange.com/q/122878/13866">Can multiple candidate blocks be mined concurrently by the miner, even if at the end only one block gets added to the chain every 10 mins?</a></p>
<ol start="2">
<li><strong>Time sync between nodes:</strong></li>
</ol>
<p>If multiple nodes start at different points, so do we need to sync the nodes so that they are operating at the same time; like say node A starts at time t1 , node B starts at time t2.. so we sync node B with node A's clock. Something like this...</p>
<p>But this would be impossible to do in a huge network tho</p>
<p>Because its said that bitcoin network mines a new block every 10 mins, so does this mean the ledger of each individual node gets updated 10 mins? So regardless of when the individual nodes start, their ledger would get updated within their 10 min time window.</p>

<synchronization><nodes>
If multiple nodes start at different points, so do we need to sync the nodes so that they are operating at the same time
RedGrittyBrick
# If multiple nodes start at different points, so do we need to sync the nodes so that they are operating at the same time

(Asked by: username_0 on 2024-05-04)

From [Can multiple candidate blocks be mined concurrently by the miner, even if at the end only one block gets added to the chain every 10 mins?](https://bitcoin.stackexchange.com/q/122878/13866)

2. **Time sync between nodes:**

If multiple nodes start at different points, so do we need to sync the nodes so that they are operating at the same time; like say node A starts at time t1 , node B starts at time t2.. so we sync node B with node A's clock. Something like this...

But this would be impossible to do in a huge network tho

Because its said that bitcoin network mines a new block every 10 mins, so does this mean the ledger of each individual node gets updated 10 mins? So regardless of when the individual nodes start, their ledger would get updated within their 10 min time window.

**Tags:** synchronization, nodes


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## 2 answers

### Answer by username_0 on 2024-05-04. Score: 0

Nodes do not need their time to be synchronised. Clocks can be up to two hours different without causing issues.

It is the proof-of-work mechanism, not time synchronisation, that ensures all nodes eventually record all the same transactions in all the same order.

> this would be impossible to do in a huge network tho

NTP easily syncs nodes to a few tens of milliseconds on a global scale.

Bitcoin doesn't need this.


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### Answer by username_1 on 2024-05-06. Score: 0

Nodes on the Bitcoin network synchronize the network state by processing the blockchain. As they validate each block and apply all transactions to their UTXO set, eventually they catch up to the best chaintip. At this point, they are synchronized with the network and know about all existing pieces of bitcoin. It is not necessary for the node’s local clocks to be synchronized, although if a node’s local time is significantly lagging behind, it may not accept some valid blocks until those blocks timestamp is less than two hours in the future from their local time.


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