Explain why a network interface that has promiscuous mode turned off would prevent a sniffer running on the host from capturing all network traffic.

In-network promiscuous mode is off then it stops or not allows the network to access or read the network packets.

Explanation:

In promiscuous mode is enabled the allows the network to access or read network packet. In this mode sometimes allows the sniffer to access the host and capture network packets. It is dangerous.

In LAN promiscuous mode can ready the network packets by network adapters when data transmitted in the network traffic.

promiscuous mode is normally supported by network adapters as an input and output device by the / operating systems.