# PowerShell script that can add ad-blocking DNS entries to the Windows hosts file
# This script defines the path to the Windows hosts file and a list of ad-blocking DNS entries. 
# It then reads the contents of the hosts file and adds the ad-blocking DNS entries to it if they are not already 
# present.
# Make sure to run this script with administrative privileges, as modifying the hosts file requires elevated permissions.

```powershell
# Define the path to the hosts file
$hostsFilePath = "$env:windir\System32\drivers\etc\hosts"

# Define the ad-blocking DNS entries
$adBlockingDnsEntries = @(
    "0.0.0.0 ad.doubleclick.net",
    "0.0.0.0 ads.yahoo.com",
    "0.0.0.0 googleadservices.com",
    "0.0.0.0 pagead2.googlesyndication.com",
    "0.0.0.0 pubads.g.doubleclick.net",
    "0.0.0.0 securepubads.g.doubleclick.net",
    "0.0.0.0 www.googleadservices.com",
    "127.0.0.1 aax-us-east.amazon-adsystem.com",
    "127.0.0.1 aax-us-west.amazon-adsystem.com",
    "127.0.0.1 aax-eu.amazon-adsystem.com"
)

# Read the contents of the hosts file
$hostsFileContents = Get-Content $hostsFilePath

# Add the ad-blocking DNS entries to the hosts file
$adBlockingDnsEntries | ForEach-Object {
    if ($hostsFileContents -notcontains $_) {
        Add-Content $hostsFilePath $_
    }
}
```