Using AD Query, the security gateway connections to the Active Directory Domain Controllers using what protocol?

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?

Which of the following enables administrators to configure and enforce MFA on a Linux system?

Which of the following technologies can be used as a central repository of Linux users and groups?

A Linux administrator would like to use systemd to schedule a job to run every two hours. The administrator creates timer and service definitions and restarts the server to load these new configurations. After the restart, the administrator checks the log file and notices that the job is only running daily. Which of the following is MOST likely causing the issue?