A technician receives a call on monday morning that several computers will not connect to the network. The technician determines that the computers left on over the weekend are functional and those that were turned off over the weekend are not functioning. Which of the following is the MOST likely source of the problem?（）

• A、DHCP is not functioning.
• B、WINS needs to be restarted.
• C、DNS is not functioning.
• D、LDAP is not functioning.