How Quad9 Connect works
Quad 9 Connect secures all your DNS transactions to our name servers. It creates an encrypted TLS connection for your DNS traffic. It does not provide VPN service for the rest of your traffic. Regardless of your DNS settings on your device Quad9 handles all DNS traffic. If you want to use a local server for a local domain you need to set that in the Quad9 connect settings.
When the Quad9 Connect app starts up it uses the VPN android APi (https://developer.android.com/guide/topics/connectivity/vpn) to establish a DNS over TLS connection to the Quad9 DNS servers. Once this connection is established all DNS queries from the device are sent over this connection that uses DNS over TLS (DoT).
When you open the Instagram app it goes to connect to several addresses within instagram.com as well as domains outside instagram for analytics, tracking and debugging purposes.
Quad9 Connect takes the DNS queries and send them out over the TLS connection to our recursive DNS Server.
Quad 9 doesn’t block instagram.com so the results are given to the Instagram app. In Quad9 Connect under statistics in the 3 line menu you will see the main page and If you select the success rate you will see the individual queries that went through the app.
The Instagram app then connects to the IP address provided by Quad9 over your regular internet connection.
Your device will do many lookups you might not be expecting. This is because each app has hosts they need to go to. This includes lookups that happen when you do not have the app open and ad sites that provide the in app ads for some apps.