Batch file that change dns between 2 option - powershell

Question

I'm trying to make a windows 10 batch file that swap my dns from 2 options. The first one is 8.8.8.8 (google dns) and the second one are a custom DNS that allows me to watch US netflix (like 90.90.90.90).
The bash command to change dns is
netsh interface ipv4 add dnsserver "Ethernet" address=8.8.8.8 index=1
the command to check which dns is up and running is:
nslookup
Now i want to do an IF THEN ELSE that work like this:
if (dns == 8.8.8.8)
then (change them to 90.90.90.90)
else (change them to 8.8.8.8)
Even a powershell script is fine

Answer 1

This should work:
#echo off
set "dns=8.8.8.8"
for /F "skip=1 tokens=2" %%a in ('nslookup^<NUL') do if "%%a" equ "8.8.8.8" set "dns=90.90.90.90"
netsh interface ipv4 add dnsserver "Ethernet" address=%dns% index=1

Answer 2

Basically:
# Setup the dos command process information:
$pinfo = New-Object System.Diagnostics.ProcessStartInfo
$pinfo.FileName = "nslookup"
$pinfo.Arguments = ""
$pinfo.UseShellExecute = $false
$pinfo.CreateNoWindow = $true
$pinfo.RedirectStandardOutput = $true
$pinfo.RedirectStandardError = $true
# Start the process:
$process.Start() | Out-Null
# Wait a while for the process to do something:
sleep -Seconds 5
# If the process is still active kill it:
if (!$process.HasExited) {
$process.Kill()
}
# get output from stdout and stderr:
$stdout = $process.StandardOutput.ReadToEnd()
$stderr = $process.StandardError.ReadToEnd()
# Parse the IP address from the output:
$regex = [regex] "\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b"
$regex.Matches($stdout) | %{ $Condition = $_.value }
# Do your dns change based on the output:
if ($Condition -eq "8.8.8.8")
{
"set other dns"
}
Else
{
"set google dns"
}
Sorry I couldn't mature the answer a bit more; unexpected visitors.
-Edit:
Taking into account some of the comments, and a bug with my regular expression, this might be a more suitable solution:
[cmdletbinding()]
param ([parameter(ValueFromPipeline=$true,ValueFromPipelineByPropertyName=$true)] [string[]]$ComputerName = $env:computername )
begin {}
process {
# get current DNS setting:
foreach ($Computer in $ComputerName) {
if(Test-Connection -ComputerName $Computer -Count 1 -ea 0)
{
try {
$Networks = Get-WmiObject Win32_NetworkAdapterConfiguration -ComputerName $Computer -EA Stop | ? {$_.IPEnabled}
}
catch
{
Write-Warning "Error occurred while querying $computer."
Continue
}
foreach ($Network in $Networks)
{
$Condition = $Network.DNSServerSearchOrder;
break;
}
}
}
# Do your dns change based on the output:
if ($Condition -eq "8.8.8.8")
{
"set other dns";
}
Else
{
"set google dns";
}
}
end {}