user62184: When does bitcoin node sync itself?
Do different types of sync in bitcoin exist (initial, periodic...)?

user208: Always.
When starting up, Bitcoin Core sends out a request to its peers to inform it about the best chains they know about (using a getheaders message). 
After that point, it is automatic: peers will immediately announce new blocks they knew about after they learn about them. This either happens using:

legacy inv mechanism, in which case just block hashes are announced
BIP130 (if negotiated), in which case announcements send full block headers
BIP152 high-bandwidth mode (if negotiated), in which case blocks are immediately transferred in full using compact blocks protocol


62184: <p>When does bitcoin node sync itself?</p>

<p>Do different types of sync in bitcoin exist (initial, periodic...)?</p>
 208: <p>Always.</p>

<p>When starting up, Bitcoin Core sends out a request to its peers to inform it about the best chains they know about (using a <code>getheaders</code> message). </p>

<p>After that point, it is automatic: peers will immediately announce new blocks they knew about after they learn about them. This either happens using:</p>

<ul>
<li>legacy <code>inv</code> mechanism, in which case just block hashes are announced</li>
<li>BIP130 (if negotiated), in which case announcements send full block headers</li>
<li>BIP152 high-bandwidth mode (if negotiated), in which case blocks are immediately transferred in full using compact blocks protocol</li>
</ul>
