I need an endpoint/ ip address to allow in firewall to white list for

My response here will be the same that I gave you through email:

The only time our server would need to contact yours is if you are running Autotune. At those times, I'd recommend just disabling the IP blocking.

Our server is run from multiple IP addresses, depending on your location, and it can change periodically. You can use any tools to determine the current IP address, but even that may not be the one that an Autotune test would use to scan your page. Also, when you run the Error Check tool, your site will need to be in "Online" mode so the HTML can be validated as well.

I hope that helps explain, but if you need anything else, just let us know.

If you have further issues or questions, just let us know.

Thanks,
Alex

No problem. As noted, you can quickly disable the protection, run our test, and re-enable if it you want to run those tests sooner. It doesn't have to be disabled for more than a minute or so.

If you do run into issues or have any other questions, just let us know.

Thanks,
Alex