Unable to add additional domain controller

The following are the possible reasons for the failures in adding additional domain controller.

1. Check the Domain Name for which the additional DC required is pingable from a host which going to become additional DC. i.e if domain name is mydnstest.com then the command ping mydnstest.com should succeed.
2. Check TcpIp settings. i.e set the dns server ip for additional dc is the ip of primary dns server.
3. Check the netbios name of the additional DC is pingable.
4. Check the primary dns server contains Type A record of additional domain controller.