An administrator has purchased monitoring software that can be configured to alert administrators when hardware and applications are having issues.  All devices are configured with SNMP， but the administrator wants to further secure the SNMP traffic.  Which of the following settings would BEST provide additional monitoring security？（）

A.Setting up a custom community name
B.Configuring the network to block traffic on port 161
C.Configuring the Windows Firewall to block port 161
D.Setting SNMP to read only on the devices
E.Installing new MIBs