DNS Header Flags and EDNS Header Flags

(last updated 2005-06-09)

Registries included below:
- DNS Header Flags 
- EDNS Header Flags (16 bits)


Registry Name: DNS Header Flags
Reference: [RFC1035]
Range                         Registration Procedures        Notes
----------------------------  -----------------------------  ------
KEY RR flag bits 2, 8-11      IETF Consensus
NAMTYP bits and bits 4 and 5  IETF Standards

Note: 
In DNS query header there is a flag field in the
second 16 bit word in query from bit 5 through 
bit 11 (RFC1035 section 4.1.1)

Registry:
Bit       Flag  Description            Reference
--------  ----  ---------------------  ---------
bit 5     AA    Authoritative Answer   [RFC1035]
bit 6     TC    Truncated Response     [RFC1035]
bit 7     RD    Recursion Desired      [RFC1035]
bit 8     RA    Recursion Allowed      [RFC1035]
bit 9           Reserved
bit 10    AD    Authentic Data         [RFC4035]
bit 11    CD    Checking Disabled      [RFC4035]


Registry Name: EDNS Header Flags (16 bits) 
Reference: [RFC2671]
Range                     Registration Procedures  Notes
------------------------  -----------------------  ------
EDNS Extended Label Type  IESG approval 
Version Number            IESG approval 
Option Code               RFC

Registry:
Bit        Flag  Description            Reference
---------  ----  ---------------------  ------------------
Bit 0      DO    DNSSEC answer OK       [RFC3225][RFC4035]
Bit 1-15         Reserved


References
----------
[RFC1035]  P. Mockapetris, "DOMAIN NAMES - IMPLEMENTATION 
           AND SPECIFICATION", RFC 1035, November 1987.

[RFC2535]  D. Eastlake, "Domain Name System Security Extensions",
           RFC 2535, March 1999.

[RFC2671]  P. Vixie, "Extension Mechanisms for DNS (EDNS0)", 
           RFC 2671, August 1999.

[RFC3225]  D. Conrad, "Indicating Resolver Support of DNSSEC", 
           RFC 3225, December 2001.

[RFC3655]  B. Wellington and O. Gudmundsson, "Redefinition of 
           DNS Authenticated Data (AD) bit", RFC 3655, November 2003.

[RFC4035]  R. Arends, R. Austein, M. Larson, D. Massey, and S. Rose, 
           "Protocol Modifications for the DNS Security Extensions", 
           RFC 4035, March 2005.

(created 2001-10-15)

[]
