Facebook.com and the iOS7 Captive Portal Detection

Question

I created a router that connects to facebook to get some info before a user may access the internet.

First they connect, get the Captive Portal Page and then continue to

Answer 1

I've just tested various router settings and noticed that iOS 7 is NOT trying to contact above mentioned sites/URLs when router's DOMAIN field is blank.

My guess is that blank domain points to a consumer-type network set up and Apple is not expecting a Captive Portal at such network. If you have access to administer your router see if you can clear out the DOMAIN field (and restart/retest).