What exactly is the remit of DNS? Is it simply for when a user wishes to visit an IP address from a browser by entering a URL? Or does the user have to be visiting a website external to the network, so what about when visiting internal web pages on the same web server etc?
On a wifi login page, if the captive portal uses IP redirection and then afterwards the user enters in their credentials- the browser has to send them to the AAA server, would DNS be used here, or only if the AAA server was external? (Or neither?). Or would the DNS kick in after the AAA server has replied, sending the user to the website they wanted/an unsuccessful login page?
I just want to understand for what actions exactly DNS is used with regards to internal/external network?
EDIT After doing some more looking around im fairly certain DNS is used within RADIUS, but could someone still confirm/explain?