I was digging into server side rendering with Angular this week. It seems architected to be totally isomorphic, so if you are getting data on the server or the client, it's the same line of code that runs. Therefore it would make a call like this.http.get('http://www.example.com/myurl'); where this.http would be an instance of Http from @angular/http.
On the client side, this is super clear. It means the browser is making an XHR request to my server.
On the server side... what is actually happening behind the scenes? I imagine the node server, being completely unaware of its domain, will make a regular http request, with DNS lookup and everything, just to find itself?
Is that accurate?
All comments point to the answer of the question being that your server will reach out for DNS call to come back and hit itself.
Since I was curious about this to know about performance, I did a test like this: time curl -v http://[mydomain].us-east-1.elb.amazonaws.com/testedself.
The endpoint is just an express endpoint with res.send('Hello World');. The extra time is ~10MS in this specific test.