Which utility is used to test if a host is reachable across an IP network?

The utility used to test if a host is reachable across an IP network is Ping. This tool sends a series of Internet Control Message Protocol (ICMP) Echo Request messages to the specified IP address and waits for Echo Reply messages. If the host is reachable, you will receive replies back, which indicate both connectivity and the time it took for the packets to reach the destination and return.

Ping is widely used for troubleshooting and verifying network configurations because it provides a straightforward way to check the status of a network connection. When you perform a Ping test, you're confirming that your device can communicate with another device across the network, which is a fundamental aspect of network diagnostics and performance evaluation.

Other utilities listed serve different purposes. For instance, Traceroute determines the path packets take to reach a destination and not just if the destination is reachable. ARP is used for resolving IP addresses into MAC addresses within a local network and does not indicate network reachability over IP. Netstat provides information about network connections and statistics but does not test connectivity directly.