无法访问PHP执行Ping目标主机

我正在我的公司局域网上ping路由器(192.168.200.254)后面的几台计算机(192.168.200.1和192.168.200.2)。

function pingAddress($TEST) {
$pingresult = exec("ping -n 1 $TEST", $output, $result);
    if ($result == 0) {
        echo "Ping successful!";
        } else {
        echo "Ping unsuccessful!";
        }

    }
pingAddress("192.168.220.1");
pingAddress("192.168.220.2");

我的问题是,其中一台计算机没有通电(.1),但我仍然得到ping响应。

Pinging 192.168.200.1 with 32 bytes of data:
Reply from 192.168.200.254: Destination host unreachable.
Ping statistics for 192.168.200.1:
Packets: Sent = 1, Received = 1, Lost = 0 (0% loss),

192.168.220.1上的var_dump($output)ping尝试显示为:

array(6) { 
[0]=> string(0) "" 
[1]=> string(44) "Pinging 192.168.200.1 with 32 bytes of data:" 
[2]=> string(57) "Reply from 192.168.200.254: Destination host unreachable." 
[3]=> string(0) "" 
[4]=> string(34) "Ping statistics for 192.168.200.1:" 
[5]=> string(56) " Packets: Sent = 1, Received = 1, Lost = 0 (0% loss)," 
}

因此,我正试图搜索为假阳性“Destination host unareachable”消息创建的$output数组,但在这条路由上运气不佳。

function pingAddress($TEST) {
$findme ="Destination host unreachable";

    $pingresult = exec("ping -n 1 $TEST  && exit", $output, $result);
        //echo $result. "<br/>";
        if (($result == 0) AND (in_array($findme, $output))){
            echo "Ping unsuccessful! <br/>";
        }
        elseif (($result == 0) AND (!in_array($findme, $output))){
            echo "Ping successful! <br/>";
        }
        elseif ($result == 1){
            echo "Ping unsuccessful! <br/>";
        }    
}
pingAddress("192.168.220.1");
pingAddress("192.168.220.2");

仍然显示成功。我可能在这里做错了什么。有什么想法吗?