How to find out where the web application sends requests?

Question

linux

There was a situation when, when accessing a PHP application (Laravel), the server responds for a long time.
In the logs, I noticed a request for some different IPs, one of them is Google. And just because of the expectation of a response from them, the application responds for a long time.
The catch is that nowhere in the code do I make requests for any third-party resources. Packages are all standard from the stall, nothing more.
What could be the reason and how is it possible to find out at the Laravel / nginx / linux level where and from where the request for these third-party ones comes from?

Answer 1

tcpdumpwill also be helpful.
There is also such a utility strace, you can pass the PID of the process, the path to the file, the name of the process as parameters to it - it can show a lot of things. Might be useful in this case.

Answer 2

wireshark help!

Answer 3

Fiddler Everywere has a nice GUI to view all requests and it's easy to see https too.