Which protocol does Ping use?

Ping uses the Internet Control Message Protocol (ICMP) to send echo request messages to a specified host and listen for echo reply messages. ICMP is primarily used for diagnostic and error-reporting purposes in the Internet Protocol suite. When a Ping command is executed, packets are sent to the target device using ICMP. This allows users to determine the reachability of the networked device and measure round-trip time for messages sent.

The other options, while important in networking, do not relate to how Ping operates. TCP is a connection-oriented protocol that ensures reliable data transmission, which is not the focus of Ping. ARP is used for resolving IP addresses to MAC addresses within a local network. BootP is a protocol related to the configuration and booting of devices on a network but does not pertain to the functionality of Ping. Thus, ICMP is the correct choice in identifying the protocol that Ping utilizes.