Hello Gong, Allen,
Thank you for posting in Q&A forum.
The error message usually indicates a connectivity or configuration issue between the Active Directory (AD) domains involved in the forest trust.
Here are a few steps you can take to troubleshoot this issue:
1.Check Network Connectivity
- Ensure that the network connection between the domains is reliable and there are no firewall blocks or network issues preventing communication.
- Use the
ping
command to verify you can reach the domain controller in the other domain.
For example:
ping the domain name of the other domain (such as, ping domain.com)
ping IP address of the Domain Controller in the other domain
ping the FQDN of the DC in the other domain (such as, ping DCName.domain.com)
2.DNS Configuration
- Verify that the DNS settings are correctly configured for both domains. Each domain should be able to resolve the DNS names of domain controllers in the other domain.
- Ensure that the DNS server has the necessary forwarders or conditional forwarders configured.
3.Active Directory Sites and Services
- Ensure that site links and replication are properly configured in Active Directory Sites and Services.
- Make sure that the domain controllers are correctly placed in their respective sites.
4.Domain Controller Availability
- Verify that the domain controllers in the other domain are up and running.
- Check the event logs on the domain controllers for any errors or warnings that might indicate why they are not being found.
5.DNS Records
- Ensure that the necessary service records (SRV records) exist in DNS for the other domain.
6.Trust Configuration
- Confirm that the trust relationship between the domains is correctly configured in Active Directory Domains and Trusts.
- Try removing and re-adding the trust relationship if necessary.
7.Firewall and Ports
- Ensure that the necessary ports for AD communications are open. Some common ports include 53 (DNS), 88 (Kerberos), 135 (RPC), 389 (LDAP), 445 (SMB), and others.
How to configure a firewall for Active Directory domains and trusts
8.Time Synchronization
- Ensure that the system clocks on both domains are synchronized. Significant time differences can cause trust issues. After checking these areas, try validating the forest trust again.
9.Check has someone made any changes in this domain and the other domain during the several minutes.
I hope the information above is helpful.
If you have any questions or concerns, please feel free to let us know.
Best Regards,
Daisy Zhou
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