What is the most probable cause of the problem?

The phone line the ceo is using is digital.-the modems use an analog phone line. it seems the phone line the ceo is trying is a digital line.incorrect answers:a: a dns server is responsible for host name to ip address resolution. it will not cause a dialup problem.b: a dhcp server is responsible for the automatic ip configuration of dhcp clients. it will not cause a dialup problem.c: a problematic remote access server would prevent the remote user from logging on to the network. however, it will not cause a no dial tone error.e: the phone line cannot be problematic as the ceo has used it to call you.references:david groth and toby skandier, network+ study guide (4th edition), sybex, alamedaca, 2005, pp. 186-188, 194.