Question about isOnline() DNS check behavior when using HTTP proxy

[tkyggit]

Hi,

First of all, thank you for maintaining this extension.

I have a question about the implementation of isOnline() in
WebRequestWorkerSingleton.

As far as I understand, isOnline() performs a DNS lookup against
www.microsoft.com to determine whether the machine is online.

I was wondering how this is expected to behave in environments where
an HTTP proxy is configured.

In many enterprise networks:

• The client machine does not resolve external DNS directly
• DNS resolution is performed by the proxy server
• HTTP/HTTPS traffic works correctly via the proxy
• But direct DNS lookups from the client may fail

In such a setup, DNS resolution failure does not necessarily mean
that the machine is offline.

So I was curious:

• Is the DNS lookup intentionally used as a simplified connectivity check?
• Is proxy-based DNS resolution considered out of scope?
• Would it make sense to instead attempt a lightweight HTTP request
  using the configured proxy settings?

I may be misunderstanding the design intention, so I would appreciate
any clarification on this.

Thank you!

[nagilson]

Thanks for your thoughtful issue writeup. Sorry, I thought I had gotten to this one already.

You're right, there's a bug here with the IsOnline check. This check is more meant to be a fallback/error handler, but it ended up being used elsewhere. It looks like I avoided using the proxy logic we have with the axios client because this was a static method and the web worker wasn't a singleton at the time and had to instantiate a client. We used to check 8.8.8.8 (google DNS server) as a base check because that's what another popular isOnline library did, and without microsoft.com working, most of our code doesn't really work anyway.

I probably thought the DNS resolution from node.js respected proxies.
Will fix based on your suggestion, thanks.