You want to create a setup servers on both Site A and Site B and have the active directory server on both ends. Site A is the main server with the AD already configured and you want to join Site B to Site A.
- Make sure the VPN is setup correctly and that you can ping each other’s server from both ends.
- Set Site B server to use the Site A’s DNS server. Check the DNS using the nslookup command and that you can ping Site A’s server from Site B using FQDN.
- When you run dcpromo and you receive a message that the domain name cannot be resolved check the domain name suffix. Either make sure the workgroup name on Site B is same as the domain name on site A or set the domain suffix to be same as the domain name on the site A.
- Run dcpromo and join the domain.
- Make sure the Site B and Site A server will have Global Catalog function.