Which statement is true when ICMP echo and echo-reply are disabled on edge devices？（）

• A、Pings are allowed only to specific devices.
• B、CDP information is not exchanged.
• C、Port scans can no longer be run.
• D、Some network diagnostic data is lost.
• E、Wireless devices need to be physically connected to the edge device.
• F、OSPF routing needs the command ip ospf network non-broadcast enabled.