Why XAMPP page appears on some website?

[MuhdNurHidayat]

As student of diploma in computer science taking course "Introduction of Database Management System" in the third semester, I leave Apache and MySQL to start with windows so that I can just use them whenever needed and also using it in class (We bring our laptops to class under lecturers instruction because a lot of computers in the lab have crashed XAMPP and many other problems like Apache freezing). But I found out that some websites doesn't load correctly and giving me the XAMPP page (the one that appear when access http://localhost/). Here's two of them:
http://www.isitdownrightnow.com/
http://www.pickthebrain.com/

Screenshots:
I can access normally when Apache and MySQL modules is stopped (favicon still showing XAMPP logo):

I see my own XAMPP page on their website when Apache and MySQL modules is running:


I have never encountered this on Windows 8.1, I've upgraded to Windows 10 two months ago and just realize about some webpages showing XAMPP page a few days ago.

XAMPP Version: 1.8.1
Control Panel Version: 3.1.0 3.1.0 [ Compiled: September 20th 2012 ]
Running with Administrator rights - good!

OS: Windows 10 Home Single Language (Build 10240)
Browser: Google Chrome version 46.0.2490.80m (tested with normal and incognito, same result)

Edge shows same result:

[Altrea]

What is the contents of your Windows HOSTS file?
What is the result of a ping to that URLs at the time XAMPP is started and XAMPP is stopped?