Please explain the problem in detail. What happens? What is the exact error messages?

There is a DNS lookup tools available as a tab on the about:networking page that you can try.

What is an example of how the no proxy option is used?

Is there a reason why you didn't choose "Use system proxy settings"

That for me is the default firefox install. Choosing No Proxy means no IP connection all internet needs IP address to connect.

A proxy service is a way to get around some censorship problems that show up on the web. Government for example.

You would connect to the proxy service, and thru it, connect to the website you want.

The proxy window on Firefox tells the browser how to connect to the service.

If you do have direct Internet access without a proxy, the 'No proxy' setting should work. It certainly does here.

To verify the DNS over HTTPS functionality (among other things) for Cloudflare's DNS service you may also try this link. https://www.cloudflare.com/ssl/encrypted-sni/

If "no proxy" is selected what network parameters is firefox using.

It can't being using the native operating parameters because there is already a value for that entry called "use system proxy settings"

First, the browser connects to the web. Then, if a proxy is selected, the browser connects to it. After a connection is made to wherever you want.

Is there a reason why you didn't choose "Use system proxy settings"

"Use system proxy settings" would have the same effect as "No Proxy" when there is no proxy set up in the global system settings.

First, the browser connects to the web. Then, if a proxy is selected, the browser connects to it.

This is nonsense. You may confuse proxy with a VPN.

That doesn't make sense why would there be 2 identical options "no proxy" and "use system proxy settings"

This is why I asked how is the no proxy used?

why would there be 2 identical options "no proxy" and "use system proxy settings"

They aren't identical, but the effect is the same under the condition explained above.

If you have set up a system wide proxy the two options would be entirely different.

I do not understand the "no proxy" option and how it should be used. The condition you explained above does not explain at what point it would decide to connect to another proxy much less how another proxy would be configured in FF.

Perhaps this can help https://support.mozilla.org/en-US/search?esab=a&w=1&q=proxy

I probably don't understand your problem.

If you have a proxy, then use whatever option fits your needs, except, 'No Proxy'. If you have multiple proxies, you'll either have to switch between them manually, or look for an extension making this more comfortable. In any case, you can only use one proxy at a time.

If you don't have a proxy, use 'No Proxy'. Simple as that.

The problem Is I do not understand how FF implements "no proxy" I have asked for an example. "no proxy" simple means no communications to the operating system, no communications with ff communications settings. So what is Firefox communicating with or how?