It depends on what you mean by "at a time". Assuming you don't mean at the exact same moment (which would be bad idea for many reasons) you can certain create a single script that checks multiple servers one after the other.
Code:
for host in host1 host2 host3 host4
do ping -c 3 $host
done
Or if you have a file with a list of servers you can do:
Code:
cat hostlistfile | while read host
do ping -c 3 $host
done