Como ping saberá que as respostas que recebeu realmente são todas ?
Para descobrir quais hosts em uma sub-rede estão ativos , algo como nmap é adequado. Veja o argumento -sn para Descoberta de Host :
-sn(No port scan)This option tells Nmap not to do a port scan after host discovery, and only print out the available hosts that responded to the scan. This is often known as a “ping scan”,[...]
Systems administrators often find this option valuable as well. It can easily be used to count available machines on a network or monitor server availability. This is often called a ping sweep, and is more reliable than pinging the broadcast address because many hosts do not reply to broadcast queries.