Question : hostname

i want exact definition for hostname ? why do we need IP address even i can ping like c:\ping (system name) ?

Answer : hostname

Machines within a domain will have names that include the domain name;for example, within sample.com domain i may have item1.sample.com,product.sample.com,anything.sample.com, etc...Those specific machine names are called hostnames. How does TCP/IP connect the English names--the hostnames--to the IP address? With Hosts,DNS & WINS...these are the process of converting a name to its corresponding IP address called "name resolution".
"Ping" is a TCP/IP utility to verify a connection within a TCP/IP network...and PING is not possible without enabling or using the TCP/IP protocol in the machine. IP address is required to identify a particular machine's IP address that can be configured statically or dynamically.