General DNS Reference Information

IPv6 addresses (AAAA)

IPv6 addresses are 128-bit identifiers for interfaces and sets of interfaces which were introduced in the DNS to facilitate scalable Internet routing. There are three types of addresses: Unicast, an identifier for a single interface; Anycast, an identifier for a set of interfaces; and Multicast, an identifier for a set of interfaces. Here we describe the global Unicast address scheme. For more information, see RFC 3587, “Global Unicast Address Format.”

IPv6 unicast addresses consist of a global routing prefix, a subnet identifier, and an interface identifier.

The global routing prefix is provided by the upstream provider or ISP, and (roughly) corresponds to the IPv4 network section of the address range. The subnet identifier is for local subnetting, much the same as subnetting an IPv4 /16 network into /24 subnets. The interface identifier is the address of an individual interface on a given network; in IPv6, addresses belong to interfaces rather than to machines.

The subnetting capability of IPv6 is much more flexible than that of IPv4: subnetting can be carried out on bit boundaries, in much the same way as Classless InterDomain Routing (CIDR), and the DNS PTR representation (“nibble” format) makes setting up reverse zones easier.

The Interface Identifier must be unique on the local link, and is usually generated automatically by the IPv6 implementation, although it is usually possible to override the default setting if necessary. A typical IPv6 address might look like: 2001:db8:201:9:a00:20ff:fe81:2b32

IPv6 address specifications often contain long strings of zeros, so the architects have included a shorthand for specifying them. The double colon (::) indicates the longest possible string of zeros that can fit, and can be used only once in an address.

Bibliography (and Suggested Reading)

Request for Comments (RFCs)

Specification documents for the Internet protocol suite, including the DNS, are published as part of the Request for Comments (RFCs) series of technical notes. The standards themselves are defined by the Internet Engineering Task Force (IETF) and the Internet Engineering Steering Group (IESG). RFCs can be obtained online via FTP at:

(where xxxx is the number of the RFC). RFCs are also available via the Web at:


RFC 974 - C. Partridge. Mail Routing and the Domain System. January 1986.

RFC 1034 - P.V. Mockapetris. Domain Names — Concepts and Facilities. November 1987.

RFC 1035 - P. V. Mockapetris. Domain Names — Implementation and Specification. November 1987.

Proposed Standards

RFC 2181 - R. Elz and R. Bush. Clarifications to the DNS Specification. July 1997.

RFC 2308 - M. Andrews. Negative Caching of DNS Queries. March 1998.

RFC 1995 - M. Ohta. Incremental Zone Transfer in DNS. August 1996.

RFC 1996 - P. Vixie. A Mechanism for Prompt Notification of Zone Changes. August 1996.

RFC 2136 - P. Vixie, S. Thomson, Y. Rekhter, and J. Bound. Dynamic Updates in the Domain Name System. April 1997.

RFC 2671 - P. Vixie. Extension Mechanisms for DNS (EDNS0). August 1997.

RFC 2672 - M. Crawford. Non-Terminal DNS Name Redirection. August 1999.

RFC 2845 - P. Vixie, O. Gudmundsson, D. Eastlake, 3rd, and B. Wellington. Secret Key Transaction Authentication for DNS (TSIG). May 2000.

RFC 2930 - D. Eastlake, 3rd. Secret Key Establishment for DNS (TKEY RR). September 2000.

RFC 2931 - D. Eastlake, 3rd. DNS Request and Transaction Signatures (SIG(0)s). September 2000.

RFC 3007 - B. Wellington. Secure Domain Name System (DNS) Dynamic Update. November 2000.

RFC 3645 - S. Kwan, P. Garg, J. Gilroy, L. Esibov, J. Westhead, and R. Hall. Generic Security Service Algorithm for Secret Key Transaction Authentication for DNS (GSS-TSIG). October 2003.

DNS Security Proposed Standards

RFC 3225 - D. Conrad. Indicating Resolver Support of DNSSEC. December 2001.

RFC 3833 - D. Atkins and R. Austein. Threat Analysis of the Domain Name System (DNS). August 2004.

RFC 4033 - R. Arends, R. Austein, M. Larson, D. Massey, and S. Rose. DNS Security Introduction and Requirements. March 2005.

RFC 4034 - R. Arends, R. Austein, M. Larson, D. Massey, and S. Rose. Resource Records for the DNS Security Extensions. March 2005.

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

Other Important RFCs About DNS Implementation

RFC 1535 - E. Gavron. A Security Problem and Proposed Correction With Widely Deployed DNS Software. October 1993.

RFC 1536 - A. Kumar, J. Postel, C. Neuman, P. Danzig, and S. Miller. Common DNS Implementation Errors and Suggested Fixes. October 1993.

RFC 1982 - R. Elz and R. Bush. Serial Number Arithmetic. August 1996.

RFC 4074 - Y. Morishita and T. Jinmei. Common Misbehaviour Against DNS Queries for IPv6 Addresses. May 2005.

Resource Record Types

RFC 1183 - C. F. Everhart, L. A. Mamakos, R. Ullmann, P. Mockapetris. New DNS RR Definitions. October 1990.

RFC 1706 - B. Manning and R. Colella. DNS NSAP Resource Records. October 1994.

RFC 2168 - R. Daniel and M. Mealling. Resolution of Uniform Resource Identifiers using the Domain Name System. June 1997.

RFC 1876 - C. Davis, P. Vixie, T. Goodwin, and I. Dickinson. A Means for Expressing Location Information in the Domain Name System. January 1996.

RFC 2052 - A. Gulbrandsen and P. Vixie. A DNS RR for Specifying the Location of Services. October 1996.

RFC 2163 - A. Allocchio. Using the Internet DNS to Distribute MIXER Conformant Global Address Mapping. January 1998.

RFC 2230 - R. Atkinson. Key Exchange Delegation Record for the DNS. October 1997.

RFC 2536 - D. Eastlake, 3rd. DSA KEYs and SIGs in the Domain Name System (DNS). March 1999.

RFC 2537 - D. Eastlake, 3rd. RSA/MD5 KEYs and SIGs in the Domain Name System (DNS). March 1999.

RFC 2538 - D. Eastlake, 3rd and O. Gudmundsson. Storing Certificates in the Domain Name System (DNS). March 1999.

RFC 2539 - D. Eastlake, 3rd. Storage of Diffie-Hellman Keys in the Domain Name System (DNS). March 1999.

RFC 2540 - D. Eastlake, 3rd. Detached Domain Name System (DNS) Information. March 1999.

RFC 2782 - A. Gulbrandsen, P. Vixie, and L. Esibov. A DNS RR for specifying the location of services (DNS SRV). February 2000.

RFC 2915 - M. Mealling and R. Daniel. The Naming Authority Pointer (NAPTR) DNS Resource Record. September 2000.

RFC 3110 - D. Eastlake, 3rd. RSA/SHA-1 SIGs and RSA KEYs in the Domain Name System (DNS). May 2001.

RFC 3123 - P. Koch. A DNS RR Type for Lists of Address Prefixes (APL RR). June 2001.

RFC 3596 - S. Thomson, C. Huitema, V. Ksinant, and M. Souissi. DNS Extensions to support IP version 6. October 2003.

RFC 3597 - A. Gustafsson. Handling of Unknown DNS Resource Record (RR) Types. September 2003.

DNS and the Internet

RFC 1101 - P. V. Mockapetris. DNS Encoding of Network Names and Other Types. April 1989.

RFC 1123 - R. Braden. Requirements for Internet Hosts - Application and Support. October 1989.

RFC 1591 - J. Postel. Domain Name System Structure and Delegation. March 1994.

RFC 2317 - H. Eidnes, G. de Groot, and P. Vixie. Classless IN-ADDR.ARPA Delegation. March 1998.

RFC 2826 - Internet Architecture Board. IAB Technical Comment on the Unique DNS Root. May 2000.

RFC 2929 - D. Eastlake, 3rd, E. Brunner-Williams, and B. Manning. Domain Name System (DNS) IANA Considerations. September 2000.

DNS Operations

RFC 1033 - M. Lottor. Domain administrators operations guide. November 1987.

RFC 1537 - P. Beertema. Common DNS Data File Configuration Errors. October 1993.

RFC 1912 - D. Barr. Common DNS Operational and Configuration Errors. February 1996.

RFC 2010 - B. Manning and P.Vixie. Operational Criteria for Root Name Servers. October 1996.

RFC 2219 - M. Hamilton and R. Wright. Use of DNS Aliases for Network Services. October 1997.

Internationalized Domain Names

RFC 2825 - IAB and R. Daigle. A Tangled Web: Issues of I18N, Domain Names, and the Other Internet protocols. May 2000.

RFC 3490 - P. Faltstrom, P. Hoffman, and A. Costello. Internationalizing Domain Names in Applications (IDNA). March 2003.

RFC 3491 - P. Hoffman and M. Blanchet. Nameprep: A Stringprep Profile for Internationalized Domain Names. March 2003.

RFC 3492 - A. Costello. Punycode: A Bootstring encoding of Unicode for Internationalized Domain Names in Applications (IDNA). March 2003.

Obsolete and Unimplemented Experimental RFC

RFC 1712 - C. Farrell, M. Schulze, S. Pleitner, and D. Baldoni. DNS Encoding of Geographical Location. November 1994.

RFC 2673 - M. Crawford. Binary Labels in the Domain Name System. August 1999.

RFC 2874 - M. Crawford and C. Huitema. DNS Extensions to Support IPv6 Address Aggregation and Renumbering. July 2000.

Obsoleted DNS Security RFCs


Most of these have been consolidated into RFC 4033, RFC 4034 and RFC 4035 which collectively describe DNSSECbis.

RFC 2065 - D. Eastlake, 3rd and C. Kaufman. Domain Name System Security Extensions. January 1997.

RFC 2137 - D. Eastlake, 3rd. Secure Domain Name System Dynamic Update. April 1997.

RFC 2535 - D. Eastlake, 3rd. Domain Name System Security Extensions. March 1999.

RFC 3008 - B. Wellington. Domain Name System Security (DNSSEC) Signing Authority. November 2000.

RFC 3090 - E. Lewis. DNS Security Extension Clarification on Zone Status. March 2001.

RFC 3445 - D. Massey and S. Rose. Limiting the Scope of the KEY Resource Record (RR). December 2002.

RFC 3655 - B. Wellington and O. Gudmundsson. Redefinition of DNS Authenticated Data (AD) bit. November 2003.

RFC 3658 - O. Gudmundsson. Delegation Signer (DS) Resource Record (RR). December 2003.

RFC 3755 - S. Weiler. Legacy Resolver Compatibility for Delegation Signer (DS). May 2004.

RFC 3757 - O. Kolkman, J. Schlyter, and E. Lewis. Domain Name System KEY (DNSKEY) Resource Record (RR) Secure Entry Point (SEP) Flag. April 2004.

RFC 3845 - J. Schlyter. DNS Security (DNSSEC) NextSECure (NSEC) RDATA Format. August 2004.

Internet Drafts

Internet Drafts (IDs) are rough-draft working documents of the Internet Engineering Task Force. They are, in essence, RFCs in the preliminary stages of development. Implementors are cautioned not to regard IDs as archival, and they should not be quoted or cited in any formal documents unless accompanied by the disclaimer that they are “works in progress.” IDs have a lifespan of six months after which they are deleted unless updated by their authors.

Other Documents About BIND

Paul Albitz and Cricket Liu. DNS and BIND. Copyright 1998 Sebastopol, CA: O’Reilly and Associates.