Get-Hostname

function Get-Hostname { # PTR lookup with timeout (in whole seconds, unfortunately)
    param( [IPAddress]$IPv4, [Int]$Timeout )

    # Resolve address within requested timeout period
    if ($Timeout) {
        $hostname = (Start-Job { [System.Net.Dns]::GetHostByAddress($input).HostName } -InputObject $IPv4 | Wait-Job -Timeout $Timeout | Receive-Job);
    # Resolve address the normal way that might take a long time to fail
    } else {
        $hostname = [System.Net.Dns]::GetHostByAddress($IPv4).HostName;
    }

    Return $hostname;
}