A Technician Is Called to a Customer Site Because the Modem

Multiple Choice

A technician is called to a customer site because the modem has failed and needs to be replaced. The technician connects the existing firewall to a modem taken from another customer site and ensures the users can reach the Internet. That night, a remote vendor tries to transfer a file to the customer's server using FTP but is unable to make the connection. There were no issues the previous night. Which of the following is the MOST likely cause of the problem?

A) The firewall rules in the router were not reconfigured for use with the newer ISP protocols.
B) The modern may have its own built-in firewall that is interfering with the communications.
C) The ISP cannot route traffic from the new modern because it came from another ISP.
D) The NAT that converts the public IP to the internal private IP of the server is using an incorrect port.