Q. How do I ping a block of hosts such as 192.168.1.0/24?
A. You can use ping or fping. The -g option generate a target list from a supplied IP netmask, or a starting and ending IP. Specify the netmask or start/end in the targets portion of the command line.
fping command
To ping the class C 192.168.1.0/24, the specified command line could look like either:
$ fping -g 192.168.1.0/24
OR
$ fping -g 192.168.1.0 192.168.1.255
ping command
You can also use ping command, enter:
for i in {1..254}; do ping -c1 192.168.1.$i; done
Reference: http://www.cyberciti.biz/faq/linux-unix-ping-a-block-of-hosts-netblock/