Why do I get error "The LDAP server is unavailable" while connecting to external domain via sync connection in SharePoint UPSA ?

Question

Hello,
I am trying to connect to external domain via UPS Account having "Replicate Directory changes" permission on external domain while creating sync connection in UPSA.
I have checked below URLS :
http://social.technet.microsoft.com/Forums/en-US/1912bf88-8fec-4b5d-9d1e-a42db8318e33/ldap-server-is-unavailable-sharepoint-2010-user-synchronization?forum=sharepointadminprevious
http://social.technet.microsoft.com/Forums/en-US/6525d3aa-9197-42a2-aea0-190b84ac8356/the-ldap-server-is-unavailable?forum=sharepointadminprevious
And looks like its network connectivity issue - and hence I have verified that port 389 is open by infra team.
Note : I am able to connect to local AD , does it make sense that port is not open for external domain ? 
Can anyone please let me know what can be the issue ? 
Your help will be highly appreciated as I am struggling to fix this issue since  quite long time but no luck yet.
Thank you in advance.
Kind regards,
Dipti Chhatrapati

Answer 1

Hi Dipti,
If you have Two-Way trust relationship then not sure if you have tried below:
Create a folder on the SharePoint server
Go to Folder properties - Security tab
Try adding user of the external domain on the folder
Please let us know if you are able to add the user or not. If you are able to add then it means that the connection and trust is proper and you should be able to create sync connection in UPA without any issues or else there is some issue with the connectivity
or the trust which is configured.
Please also make sure that you have given permissions to sync account as per below TechNet:
http://technet.microsoft.com/en-us/library/hh296982(v=office.15).aspx
Replicate Directory changes permissions are also required on cn=configuration container, below are the steps:
Grant Replicate Directory Changes permission on the cn=configuration container
Use this procedure to grant Replicate Directory Changes permission on the cn=configuration container to an account.
To grant Replicate Directory Changes permission on the cn=configuration container
On the domain controller, click Start, click Run, type adsiedit.msc, and then click OK.
If the Configuration node is not already present, do the following:
In the navigation pane, click ADSI Edit.
On the Action menu, click Connect to.
In the Connection Point area of the Connection Settings dialog box, click Select
a well know Naming Context, select Configuration from the drop-down list, and then click OK.
Expand the Configuration node, right-click the CN=Configuration... node, and then click Properties.
In the Properties dialog box, click the Security tab.
In the Group or user names section, click Add.
Type the name of the synchronization account, and then click OK.
In the Group or user names section, select the synchronization account.
In the Permissions section, select the Allow check box next to the Replicating
Directory Changes (Replicate Directory Changes on Windows Server 2003) permission, and then click OK.
Kind regards,
Bhavik K Jain
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