<#
Alan Kaplan 5/29/20
This is resolves a computer name from IP
#>

param (
    [Parameter(Mandatory = $true)]
    [string]
    $IPAddress
)

Function Test-IsIP ($strTest) { 
    [Net.IPAddress]::TryParse($strTest, [ref]$null) 
}

Function Get-HostName($IP) {
    Try {
 ([System.Net.DNS]::GetHostByAddress($IP)).hostName 
    }
    Catch {
        Write-Warning "Not resolved"
    }
}


if (Test-IsIP $ipAddress) { 
    $retVal = Get-HostName $ipAddress 
}
Else {
    $retVal = "$IPAddress is not a valid IP"
}
$retVal