my @bonds = qw(bond2 bond3 bond4 bond6 bond7 bond8);
my %ipaddress_namei;

while (my @bonds_with_invalid_ip = grep { not exists $ipaddress_namei{$_}, $_ }, @bonds) {
    for my $bond (@bonds_with_invalid_ip) {
        printf "Enter IP address of %s\n", ucfirst($bond);
        my $bond_in = <STDIN>; 
        chomp($bond_in);
        if (is_ipv4($bond_in)) {
            $ipaddress_namei{$bond} = {$bond_in};
        }
    }
}