After a new installation of a DNS server, I received the following error on my DNS server every time it started :

Event ID : 4515
Source : DNS
The zone was previously loaded from the directory partition MicrosoftDNS but another copy of the zone has been found in directory partition . The DNS Server will ignore this new copy of the zone. Please resolve this conflict as soon as possible. If an administrator has moved this zone from one directory partition to another this may be a harmless transient condition. In this case, no action is necessary. The deletion of the original copy of the zone should soon replicate to this server.
If there are two copies of this zone in two different directory partitions but this is not a transient caused by a zone move operation then one of these copies should be deleted as soon as possible to resolve this conflict.
To change the replication scope of an application directory partition containing DNS zones and for more details on storing DNS zones in the application directory partitions, please see Help and Support.

Solution:

Open MMC (Management Console)

Add “ADSI Edit”
Connect to naming context : Domain
Select CN=System > CN=MicrosoftDNS

Here you see the different DNS zones which are located in your Active Directory.
Now connect to the other Directory Partitions in AD:

Connect to naming context : DC=ForestDNSZones, DC=, DC=
Also connect to naming context : DC=DomaniDNSZones, DC=, DC=

When you look in both the Directory Partitions you will see a CN=MicrosoftDNS.
Now you can look at which DNS zone is causing the conflict and delete the zone from AD.

Be sure to have a good backup before starting to delete objects from AD!