DNS not working properly

Forest scheme:
Windows server 2003
One forest with three domains (parent.local, child.parent.local, child2.parent.local)
All DCs are GC and DNS
NAT server (2k3) using RIP version 2
Replication is complete
Issue:
Parent CANNOT ping to any child domain by netbios name
Parent CAN ping by IP and by FQDN
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Child 1CAN ping parent by Netbios name, and by IP, and CAN also NSLOOKUP parent
Child 1 CANNOT ping child 2 domain by Netbios name
Child 1 CAN ping child 2 domain by IP or FQDN
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Child 2 CAN ping parent by Netbios name and by IP
Child 2 CANNOT ping Child 1 by Netbios name
Child 2 CAN ping Child 1 by IP
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What I have done so far to fix issue
Change zones to Primary Zone (remove AD Integrated)
Delete zones
Flush DNS
Net Stop Netlogon
Net Start Netlogon
Re-Create zones
When I got fedup, dcpromo all DC to remove AD, dcpromo to promote to DC, same problem.
All zones are set to zone transfer, and all name servers are included in the name servers tab.