Answer Description

Using "Ping -a" will tell the ping tool to resolve an IP Address to a hostname before beginning to ping the IP Address. If a hostname is not resolved, ping will not provide a hostname and instead show the IP address. For example, if a PC has a hostname of SERVER1 and an IP of 192.168.1.101, using Ping -a 192.168.1.101 will produce "Pinging SERVER1 [192.168.1.101] with 32 bytes of data:" at the start of output.

Wikipedia

ping is a computer network administration software utility used to test the reachability of a host on an Internet Protocol (IP) network. It is available for virtually all operating systems that have networking capability, including most embedded network administration software. Ping measures the round-trip time for messages sent from the originating host to a destination computer that are echoed back to the source. The name comes from active sonar terminology that sends a pulse of sound and listens for the echo to detect objects under water.Ping operates by means of Internet Control Message Protocol (ICMP) packets. Pinging involves sending an ICMP echo request to the target host and waiting for an ICMP echo reply. The program reports errors, packet loss, and a statistical summary of the results, typically including the minimum, maximum, the mean round-trip times, and standard deviation of the mean. The command-line options of the ping utility and its output vary between the numerous implementations. Options may include the size of the payload, count of tests, limits for the number of network hops (TTL) that probes traverse, interval between the requests and time to wait for a response. Many systems provide a companion utility ping6, for testing on Internet Protocol version 6 (IPv6) networks, which implement ICMPv6.