6. IANA Considerations

   [RFC4034] contains a review of the IANA considerations introduced by
   DNSSEC.  The following are additional IANA considerations discussed
   in this document:

   [RFC2535] reserved the CD and AD bits in the message header.  The
   meaning of the AD bit was redefined in [RFC3655], and the meaning of
   both the CD and AD bit are restated in this document.  No new bits in
   the DNS message header are defined in this document.

   [RFC2671] introduced EDNS, and [RFC3225] reserved the DNSSEC OK bit
   and defined its use.  The use is restated but not altered in this
   document.