The following knowledgebase explains the issue when client machines take too long to log on to domain:
Client computers use DNS to find the domain controller. If DNS is not running or SRV records of domain controllers are not registered then client computers will not be able to log on to the domain.
You can use the following tools to verify the SRV registration in the domain:
The above command will display if there is any problem with the SRV records of the domain controller.
If all the client computes in your network are taking too long to log on to the network then please verify if the SRV records of the domain controllers are registered in the domain.
You can use the following options to re-register the SRV records of a domain controller in the DNS:
- Restart the Netlogon Serivce.
- Use DcDiag /fix or NetDiag /fix
- Local the Netlogon.dns file in \Windows\System32\Config directory and manually add them into the DNS Zone of that domain.