How to make ping more persistent with unresolved hostnames

Question

When I try to ping a hostname of a computer that is down, I get en error that it cannot resolve the hostname.

$ alice:~ me$ ping bob
ping: cannot resolve bob: Unknown host

Is there a way I can make ping more persistent? I want it to keep trying so I can see when bob comes back online.

Answer 1

a)

while true; do
    ping bob || sleep 1
done

or

until ping bob; do
    sleep 1
done

or b) Configure a name resolution method that doesn't rely on the target host being up. /etc/hosts for the lazy.