Which two messages are used in a ping command?

The correct answer includes "ICMP Echo Request" and "ICMP Echo Reply" because the ping command operates using the Internet Control Message Protocol (ICMP) to test connectivity between two network devices. When a ping command is issued, it sends out an ICMP Echo Request message to the target device. The target device, if reachable, responds with an ICMP Echo Reply message. This process allows the originating device to determine whether the target is active and how long it takes to send and receive the message, providing insights into the latency and availability of the network.

In contrast, the other options reference protocols that are not involved in the functionality of the ping command. ARP (Address Resolution Protocol) deals with mapping IP addresses to MAC addresses, which is essential for devices on the same local network segment but not for the testing of connectivity across networks. TCP (Transmission Control Protocol) messages like SYN and ACK are used in creating sessions for reliable data transmission rather than testing reachability, and UDP (User Datagram Protocol) does not include echo messages since it is a connectionless protocol that does not establish a reliable session. Therefore, those alternatives do not apply to the functionality of the ping command.