What is the impact of an incorrectly configured default gateway on a host?

When a default gateway is incorrectly configured on a host, it primarily affects the host's ability to communicate with devices that are outside its local network. The default gateway serves as an access point for the host when trying to reach destinations outside the local subnet. If the default gateway is not set correctly, packets destined for outside networks cannot be routed properly, resulting in failure to communicate with those remote hosts.

In this scenario, while communication within the same local network would still function correctly (assuming local addressing is correct), any attempts to reach devices located in different networks would fail. This is because the host would not know where to send those packets meant for external addresses, leading to issues in network connectivity beyond the local segment. Thus, the impact of an incorrectly configured default gateway is that the host cannot communicate with hosts in other networks.