Check every Domain Controller

This handy little powershell script will check connectivity to every domain controller found in your current context.

import-module activedirectory

$alls = ((Get-ADForest).Domains | %{ Get-ADDomainController -Filter * -Server $_ } ).HostName

foreach ($server in $alls) {
        write-host $server "connection possible over 389:" (test-netconnection $server -port 389).tcptestsucceeded
}

You will need the Powershell Active Directory tools installed on your system