Get and Set DNS search order using PowerShell

Get DNS

Scenario: I was asked to generate a list of servers that were still using our old DNS servers. This script was included in an SCCM DCM baseline to generate the report.

try{

$isComplaint = $true

$Interface = Get-WMIObject Win32_NetworkAdapterConfiguration | where{$_.IPEnabled -eq “True” -and $_.IPAddress -like "10.*"} -ErrorAction Stop

Foreach($NIC in $Interface) {

$IPs = $NIC.DNSServerSearchOrder

Foreach($IP in $IPs) {

if(($IP -eq 'your.old.DNS.ip') -or ($IP -eq 'your.old.DNS.ip2')) {

$isComplaint = $false

return "Non-Compliant"

}

}

}

if ($isComplaint -eq $true) {

return "Compliant"

}

}

catch{

return "Error"

}

Set DNS

Scenario: Configure new DNS server in DNS search order for those servers still using old DNS server. For this, we created a SCCM task sequence consisting of following script and deployed to a collection of computers. The DNS server list was passed through a TS variable "DNSservers". If you are only intrested about the PowerShell portion, then pass the DNS server list in the following format $DNSServers = “198.168.1.10",”198.168.1.2". The reason why we didnt directly ran the script on all servers was because there were a mixture of domain and workgroup servers that needed this change. We were able to run the script all servers using SCCM without bothering about the connection/authentication challenges.

$logfile = 'C:\Windows\Temp\SetDNS.log'

function writetolog([string] $txt) {

$Stamp = (Get-Date).toString("yyyy/MM/dd HH:mm:ss")

Add-content $logfile -value $Stamp':'$txt

}

try{

$tsenv = New-Object -COMObject Microsoft.SMS.TSEnvironment

$DNSServers = $tsenv.Value("DNSservers")

write-host "Retrieved DNS servers list successfully"

writetolog("Retrieved DNS servers list successfully : " + $DNSServers)

$DNSServers = $DNSServers -split ','

}

catch{

write-host "Cannot retrieve DNS servers list"

writetolog("Retrieved DNS servers list successfully")

exit -1

}

#$DNSServers = “198.168.1.10",”198.168.1.2"

try{

$Interface = Get-WMIObject Win32_NetworkAdapterConfiguration | where{$_.IPEnabled -eq “True” -and $_.IPAddress -like "10.*"} -ErrorAction Stop

write-host "Connected to WMI succesfully and interfaces retrieved"

writetolog("Connected to WMI succesfully and interfaces retrieved")

Foreach($NIC in $Interface) {

try{

$NIC.SetDNSServerSearchOrder($DNSServers)

write-host "DNS servers configured successfully"

writetolog("DNS servers configured successfully")

exit 0

}

catch{

write-host "Cannot set DNS servers"

writetolog("Cannot set DNS servers")

exit -1

}

}

}

catch{

write-host "Cannot connect to WMI"

writetolog("Cannot connect to WMI")

return -1

}