Which tool is used to troubleshoot network connectivity issues by sending echo requests to a target IP address?

The tool used to troubleshoot network connectivity issues by sending echo requests to a target IP address is ping. This utility operates by sending Internet Control Message Protocol (ICMP) echo request packets to the specified IP address and waits for a response. If the target host is reachable, it sends back ICMP echo reply packets, allowing the user to determine whether the network connection is functioning. Furthermore, ping provides information such as response time and packet loss, which can be useful in diagnosing the quality of the connection.

In contrast, other options serve different purposes: ipconfig is primarily used for viewing and managing network settings on Windows machines, tracert traces the route packets take to reach a destination, providing hop-by-hop information about the path taken across the network, and nslookup is used for querying DNS to obtain domain name or IP address mapping. While these tools are valuable for network troubleshooting, only ping specifically addresses connectivity by measuring response times and packet loss through echo requests.