check-hostnames_and_ip_change

# first create a CSV with headers
# hostname;ip;dateadded;
# and add your first entries
# google.com;173.194.69.103;2017-06-05

if ($my_error){
    Clear-Variable my_error
}

$hosts_csv_path = "\\PathToCsv\hostAndIp.csv"
$hosts_csv = Import-Csv $hosts_csv_path -Delimiter ";" -ErrorVariable +my_error
$host_list = $hosts_csv | Group-Object -Property hostname -ErrorVariable +my_error

$results = @()
foreach ($host_single in $host_list){
    $hostname = $host_single.Name
    $host_ips = [System.Net.Dns]::GetHostAddresses("$hostname")
    if ($?){
        $host_ips.ipaddresstostring
        foreach ($Host_ip in $Host_ips){
            if (!($host_single.group.ip -contains $Host_ip.ipaddresstostring)){
                $line = "" | select hostname, ip, dateadded
                $line.hostname = $hostname
                $line.ip = $Host_ip.ipaddresstostring
                $line.dateadded = Get-Date -Format ("yyyy-MM-dd")
                $line
                $results += $line
            }
        }
    }
}
if ($results){
    Send-MailMessage -SmtpServer SmtpServer -To email -From email -Subject "Hostname ip change" -Body $(($results | foreach {"$($_.ip) $($_.hostname)"}) -join "`n")
    $results | Export-Csv -Append $hosts_csv_path -NoTypeInformation -Encoding utf8 -Delimiter ";" -ErrorVariable +my_error
}