DNS Protocol

Protocols/dns.md

@@ -0,0 +1,41 @@
+# DNS
+
+## Quick Information
+
+| Information |                                                                |
+| ----------- | -------------------------------------------------------------- |
+| Version     | 1.0.0                                                          |
+| Type        | Protocol                                                       |
+
+## Technical Details
+
+DNS defines a method of looking up hostnames in the context of protocols.
+
+Any computer can broadcast a `lookup` for a hostname/protocol pair and will receive a `lookup response` from computers who identify themselves with the corresponding hostname/protocol pair.
+
+Because it's not just hostnames but hostname/protocol pairs, there can be several computers using the same hostname for serving different protocols.
+
+A computer can identify himself with every hostname/protocol pair he wants and with as many hostname/protocol pairs as he wants, as long as there are no duplicated hostname/protocol pairs in the world. The computer HAS TO lookup a hostname/protocol pair before identifying with it, if it is taken, the computer is NOT ALLOWED to identify with it.
+
+Packets are composed of 3 strings:
+* the package type
+* the hostname
+* the protocol
+
+These strings are combined in a table:
+
+```
+  {
+  sType = "<package type>"
+  sHostname = "<hostname>"
+  sProtocol = "<protocol>"
+  }
+```
+
+### Looking up a hostname/protocol pair
+
+* The uplooking computer broadcasts a package of type `lookup`, where the hostname and protocol string are the hostname/protocol pair to look up.
+* If a computer identifies himself with that hostname/protocol pair, it responds directly to the uplooking computer with a package of type `lookup response`, where the hostname and protocol strings are the hostname/protocol pair, the responding computer identifies himself with.
+
+## Aviable APIs
+* [Rednet API](http://www.computercraft.info/wiki/Rednet_(API)) from CC 1.6 onward