A Linux engineer set up two local DNS servers (10.10.10.10 and 10.10.10.20) and was testing email connectivity to the local mail server using the mail command on a local machine when the following error appeared:

The local machine DNS settings are:

Which of the following commands could the engineer use to query the DNS server to get mail server information?

A. dig @example.com 10.10.10.20 a
B. dig @10.10.10.20 example.com mx
C. dig @example.com 10.10.10.20 ptr
D. dig @10.10.10.20 example.com ns