A technician has completed the installation and configuration of a third email server. The technician has configured the firewall to permit email traffic, but the mail is only being received by the two older servers. Which of the following should the technician configure to ensure incoming email will be processed by all three servers? 

Answer options:

A. Enable NTP to ensure all three servers are synchronized.
B. Configure IMAP on the new mail server.
C. Add the DNS server option in DHCP.
D. Update the MX record in DNS.

D