As you can see, Quad9 provides both secure and non-secure access. Of course, the provider recommends using secure connections, which apply DNSSEC and blacklist filters. However, if you’re looking for an entirely unfiltered browsing experience (along with the danger of exposing yourself to risks), you can access the non-secure IP addresses. Quad9 provides two IP addresses, both of which can be entered in your operating system settings. In the event that one of the communication channels is temporarily unavailable, the system can, therefore, switch directly to the other address.
Quad9 also provides an EDNS Client Subnet. This is primarily designed for Content Delivery Networks (CDNs). This type of network is used to make media files available on websites without overloading the central server. The EDNS performs load balancing and can answer CDN requests more rapidly. IoT providers are also involved in order to ensure secure DNS access for smart objects.
If you want to use one of the two encrypted connections, you have to use specific ports. For DoT, you need to use Port 853 and for DoH you need to use the standard HTTP port 443.
Quad9 doesn’t use just one DNS server. If you choose to use the service, your request will be forwarded by Anycast to one of more than 100 servers located all around the globe. With Anycast, multiple servers have the same address, but the system always selects the shortest path.