TTL

This handy little thing will identify the Operating System on one or more servers, using the OS’s default TTL value as a trigger.
(Some OS’ uses different TTL values. Most of them are listed on this site.)

cls
 $servers = "Server1","Server2" 

foreach ($server in $servers) 

{ 
$TTL = Test-Connection $server -Count 1 | select -exp ResponseTimeToLive

    Switch($TTL)
    {
        {$_ -le 64} {"$server runs Linux OS"; break}
        {$_ -le 128} {"$server runs Windows OS"; break}
        {$_ -le 255} {"$server runs UNIX OS"; break}
    }
}

– F