The Verification process of a domain .COM, .NET, .ORG or .INFO begins with the verification of the registrant's e-mail. As you forward your request to change any eventual data of your domain you will receive, on your registration e-mail, a message including a validation link on which you have to click to process the verification procedure.
For new registration the verification process has to be completed in 15 days. Otherwise, the domain will be suspended. In case you ask for a change of data for an already existing domain the process of verification has to be completed in 7 days.
If you run out of time, the domain is suspended and the register will configure the temporary Nameservers automatically. As you complete the verification process the register will configure the Nameservers registered in the registration/change request.