net: remove two dns header flags

net/dns/dns_protocol.h

Index: net/dns/dns_protocol.h
diff --git a/net/dns/dns_protocol.h b/net/dns/dns_protocol.h
index 416738a2bedee12b45db1f243ac826aee4e80866..2df327158912ddc2422b8d85b270ff763e16aec4 100644
--- a/net/dns/dns_protocol.h
+++ b/net/dns/dns_protocol.h
@@ -135,12 +135,12 @@ static const uint8_t kRcodeNXDOMAIN = 3;
 static const uint8_t kRcodeNOTIMP = 4;
 static const uint8_t kRcodeREFUSED = 5;
 
-// DNS flags.
+// DNS header flags.
+//
+// https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-12
 static const uint16_t kFlagResponse = 0x8000;
-static const uint16_t kFlagRA = 0x80;
-static const uint16_t kFlagRD = 0x100;
-static const uint16_t kFlagTC = 0x200;
-static const uint16_t kFlagAA = 0x400;
+static const uint16_t kFlagRD = 0x100;  // Recursion Desired - query flag.
+static const uint16_t kFlagTC = 0x200;  // TrunCated - server flag.

[eroman, 2017/03/04 01:44:16]

TrunCated --> Truncated

[tfarina, 2017/03/04 22:20:07]

Done. It was to emphasize why it is TC. But I guess any reader can guess that
from "Truncated" as well.

 
 }  // namespace dns_protocol