Create DOH.md

DOH.md

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+# Tenta DNS and DNS over HTTPS (DoH)
+After a lengthy iteration, we are finally launching our v2 DNS resolver, incorporating hundreds of fixes and improvements.
+Tenta DNS at its core, is about 3 things, speed, precision and privacy, this is why besides the standard tcp, and udp protocols, we support DNS-over-TLS and DNS-over-HTTPS. What we have learned from the first iteration, we perfected in this one, Tenta DNS has always-on DNSSEC validation, a more robust handling of the occasional implementation inconsistencies,
+and a caching subsystem tailored specifically for a DNS resolver, finally, our DNS-over-TLS service is active (albeit, probably unused in the vast majority of cases) during upstream queries too.
+
+To use DNS-over-HTTPS, we have set up 2 domains, https://opennic.tenta.io/dns-query and https://iana.tenta.io/dns-query, which use OpenNIC and ICANN root servers, respectively.
+The querying works in a REST API fashion, it takes 2 arguments `name` and `type` (eg: https://opennic.tenta.io/dns-query?name=example.com&type=A) and provides an answer in JSON format.  
+We opted for a simplified JSON API approach to DoH, because it removes the difficulty of including DNS queries into lightweight applications.
+
+Our response format for DoH queries is as follows:  
+**Status**: integer; analogous to classic DNS message's RCODE  
+**TC**, **RD**, **RA**, **AD**, **CD**: boolean; relevant flags describing the nature of the DNS response, same as in a classic DNS message  
+**Question**: structure (string, integer), describing the queried name, and the queried type  
+**Answer**, **Authority**, **Additional**: array of structures (string, integer, integer, string); describing every DNS records name, type, and TTL value and their record-specific data.
+
+An _example_ response (to the _example_ request) is
+```javascript
+{
+  "Status":0,
+  "TC":false,
+  "RD":true,
+  "RA":true,
+  "AD":false,
+  "CD":false,
+  "Question":[
+    {"Name":"example.com","Type":1}],
+  "Answer":[
+    {"Name":"example.com.","Type":1,"TTL":86400,"Data":"93.184.216.34"},
+    {"Name":"example.com.","Type":46,"TTL":86400,"Data":"A 8 2 86400 20180627015845 20180606075626 4354 example.com. gpgx3XIhF4XZg5Nw0eo7TmCD1zfKX9YtMq9PuSh3eAc4fJrvyS/VWy2bz/KYhgiXQe6PvtOLZbgTT2O9knkHIlAsmnznEowSrgWYaCkkkNnoC8Ii1Ikg87PCZ7FffTposk/4HRG6yXZlo9+++YZAfAC0cc9FFYpQXqxVLf9/aDQ="}]
+}
+```