You are the senior administrator of the network presented in the image below. Clients on a new floor are getting their IP addresses successfully, they can print to a network printer on the same floor, and they can use the VoIP system like all other users in the building. However, they cannot join the domain, use mail, or use intranet services. You know for certain that one of the junior administrators did the DHCP configuration for the new floor, so you ask him to check the settings. Which of the following statements present valid causes of this problem? Select all answers that apply: A. The DNS settings are not correct. B. The RIS settings are not correct. c. The mask settings are not correct. D. The default gateway settings are not correct. E. The telephony settings are not correct