Is it necessary Password Synchronization on a Hybrid infrastructure to Access Exchange Online Archiving ??

Could I use these components??

1) For user aprovisioning on Exchange Online >> Manually

2) For authentication >> ADFS

Is it necessary Password Synchronization on a Hybrid infrastructure to Access Exchange Online Archiving ??

Could I use these components??

1) For user aprovisioning on Exchange Online >> Manually

2) For authentication >> ADFS

No, not necessary 

1) Yes.

2) ) Yes

So, if we have ADFS... what is the reason to use Password Synchronization ??

So, if we have ADFS... what is the reason to use Password Synchronization ??

It can be implemented as a backup or DR in case the on-prem ADFS ever fails.

On technet document (EDAHybrid2010_09.pdf) I found this information "Active Directory synchronization between the on-premises and the Office 365 organizations is a requirement for configuring a hybrid deployment"..

So, i think we need a Synchronization server....not ?

I think that DirSync Server is necessary to synchronize some attributes:

msExchArchiveGuid
msExchArchiveName
msExchElcMailboxFlags
msExchRemoteRecipientType