Question : Domain Controller and DNS zones/replication

I have 2 Windows 2003 Standard domain controllers.  One of them runs web services for an in-house application.  People connect to application through this service on IIS on Domain Controller.  This morning no one could connect.  I believe the problem is related to this:

The dynamic registration of the DNS record '_ldap._tcp.DataCenter._sites.DomainDnsZones.COUNTRY.DOMAIN.CORP 600 IN SRV 0 100 389 DC.COUNTRY.DOMAIN.CORP failed on the following DNS server:  

DNS server IP address:
Returned Response Code (RCODE): 0
Returned Status Code: 0  

For computers and users to locate this domain controller, this record must be registered in DNS.  

USER ACTION  
Determine what might have caused this failure, resolve the problem, and initiate registration of the DNS records by the domain controller. To determine what might have caused this failure, run DCDiag.exe. You can find this program on the Windows Server 2003 installation CD in Support\Tools\support.cab. To learn more about  DCDiag.exe, see Help and Support Center. To initiate registration of the DNS records by  this domain controller, run 'nltest.exe /dsregdns' from the command prompt on the domain  controller or restart Net Logon service. Nltest.exe is available in the Microsoft Windows  Server Resource Kit CD.
  Or, you can manually add this record to DNS, but it is not recommended.  

ADDITIONAL DATA
Error Value: A socket operation was attempted to an unreachable host.

For more information, see Help and Support Center a

Answer : Domain Controller and DNS zones/replication

Open the path in the DNS ldap._tcp.DataCenter._sites.DomainDnsZones.COUNTRY.DOMAIN.CORP
Are the records are exist
if not then
Run ipconfig /registerdns
Run nslookup and type gc._msdcs.alwatan.local
are you able to get the global catalog server list
Open site and services, and check the replication connection, are they exist, if yes then force the replication and check even log

On important thing is :
if the server do this from it self without any previous modification, then you need to check the Recent installed updates and drivers, some drivers or updates couse this problem