To determine if a remote host is reachable, use the ping command as follows:
% ping hostname
If the host is accepting ICMP transmissions, the following message is displayed:
hostname is alive
This message indicates that the host responded to the ICMP request. However, if the host is down, cannot receive the ICMP packets, or if there is a routing problem between your host and the remote host, you receive the following response from the ping command:
no answer from hostname