Which protocol is used to test and verify network connectivity?

The protocol used to test and verify network connectivity is Ping, which operates using the Internet Control Message Protocol (ICMP). Ping works by sending an echo request to a specific IP address and then waiting for an echo reply. This process helps determine not only if a device is reachable over the network but also provides information about the round-trip time taken for packets to travel to the destination and back. It's a vital tool for network troubleshooting, allowing administrators to assess the status and responsiveness of devices within a network.

In contrast, Hypertext Transfer Protocol (HTTP) is primarily used for transferring web pages and is not designed for connectivity testing. File Transfer Protocol (FTP) focuses on transferring files between clients and servers, while Simple Network Management Protocol (SNMP) is used for network management and monitoring, not for basic connectivity checks. Therefore, the capability and specific purpose of Ping/ICMP for connectivity verification make it the correct choice in this context.