After Installing child domain in Windows 2012 R2 RTM causes the replication to fail.

Symptoms : Event ID 1202, 1126 and 1645

Evet ID 1202

Event ID 1126

Event ID 1645

After installing new child domain and join it to the Root domain

To show the child domain’s DNS partition enlisting use

Dnscmd /enumdirectorypartitions

Add child domain’s DNS to the forest

dnscmd /enlistdirectorypartition

First Solution

Make sure windows is full updated, After you apply Windows update the problem should be gone.

If not check the second solution:

Second: Make sure that your Child administrator and root administrator’s passwords are not identical.

Third: Make sure trust is set properly using the following command