Get Users matching a Domain in User Information List.
# Run with SharePoint 2010 Management Shell
$webUrl = "http://SharePoint"
$web = Get-SPWeb $webUrl
#$list = $web.Lists["User Information List"]
$user = Get-SPUser -web $web -Limit All | Where-Object {$_.UserLogin -Like "*AD\*"} | Format-Table -Autosize | Out-File D:\Indra\Users.txt
Write-Host Done.
Change the URL and out-put file path as per the need.