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;
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,
"IPv6 Global Unicast Address Format."
IPv6 unicast addresses consist of a
global routing prefix, a
subnet identifier, and an
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
like 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:
IPv6 address specifications often contain long strings
of zeros, so the architects have included a shorthand for
them. The double colon ("::") indicates the longest possible
of zeros that can fit, and can be used only once in an address.
Bibliography (and Suggested Reading)
Requests 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 at:
[RFC974] Mail Routing and the Domain System. January 1986.
[RFC1034] Domain Names — Concepts and Facilities. November 1987.
[RFC1035] Domain Names — Implementation and
Specification. November 1987.
[RFC2181] Clarifications to the DNS
Specification. July 1997.
[RFC2308] Negative Caching of DNS
Queries. March 1998.
[RFC1995] Incremental Zone Transfer in DNS. August 1996.
[RFC1996] A Mechanism for Prompt Notification of Zone Changes. August 1996.
[RFC2136] Dynamic Updates in the Domain Name System. April 1997.
[RFC2671] Extension Mechanisms for DNS (EDNS0). August 1997.
[RFC2672] Non-Terminal DNS Name Redirection. August 1999.
[RFC2845] Secret Key Transaction Authentication for DNS (TSIG). May 2000.
[RFC2930] Secret Key Establishment for DNS (TKEY RR). September 2000.
[RFC2931] DNS Request and Transaction Signatures (SIG(0)s). September 2000.
[RFC3007] Secure Domain Name System (DNS) Dynamic Update. November 2000.
[RFC3645] Generic Security Service Algorithm for Secret
Key Transaction Authentication for DNS
(GSS-TSIG). October 2003.
DNS Security Proposed Standards
[RFC3225] Indicating Resolver Support of DNSSEC. December 2001.
[RFC3833] Threat Analysis of the Domain Name System (DNS). August 2004.
[RFC4033] DNS Security Introduction and Requirements. March 2005.
[RFC4034] Resource Records for the DNS Security Extensions. March 2005.
[RFC4035] Protocol Modifications for the DNS
Security Extensions. March 2005.
Other Important RFCs About DNS
[RFC1535] A Security Problem and Proposed Correction With Widely
Deployed DNS Software. October 1993.
[RFC1536] Common DNS Implementation
Errors and Suggested Fixes. October 1993.
[RFC1982] Serial Number Arithmetic. August 1996.
[RFC4074] Common Misbehaviour Against DNS
Queries for IPv6 Addresses. May 2005.
Resource Record Types
[RFC1183] New DNS RR Definitions. October 1990.
[RFC1706] DNS NSAP Resource Records. October 1994.
[RFC2168] Resolution of Uniform Resource Identifiers using
the Domain Name System. June 1997.
[RFC1876] A Means for Expressing Location Information in the
Name System. January 1996.
[RFC2052] A DNS RR for Specifying the
Services. October 1996.
[RFC2163] Using the Internet DNS to
Conformant Global Address Mapping. January 1998.
[RFC2230] Key Exchange Delegation Record for the DNS. October 1997.
[RFC2536] DSA KEYs and SIGs in the Domain Name System (DNS). March 1999.
[RFC2537] RSA/MD5 KEYs and SIGs in the Domain Name System (DNS). March 1999.
[RFC2538] Storing Certificates in the Domain Name System (DNS). March 1999.
[RFC2539] Storage of Diffie-Hellman Keys in the Domain Name System (DNS). March 1999.
[RFC2540] Detached Domain Name System (DNS) Information. March 1999.
[RFC2782] A DNS RR for specifying the location of services (DNS SRV). February 2000.
[RFC2915] The Naming Authority Pointer (NAPTR) DNS Resource Record. September 2000.
[RFC3110] RSA/SHA-1 SIGs and RSA KEYs in the Domain Name System (DNS). May 2001.
[RFC3123] A DNS RR Type for Lists of Address Prefixes (APL RR). June 2001.
[RFC3596] DNS Extensions to support IP
version 6. October 2003.
[RFC3597] Handling of Unknown DNS Resource Record (RR) Types. September 2003.
DNS and the Internet
[RFC1101] DNS Encoding of Network Names
and Other Types. April 1989.
[RFC1123] Requirements for Internet Hosts - Application and
Support. October 1989.
[RFC1591] Domain Name System Structure and Delegation. March 1994.
[RFC2317] Classless IN-ADDR.ARPA Delegation. March 1998.
[RFC2826] IAB Technical Comment on the Unique DNS Root. May 2000.
[RFC2929] Domain Name System (DNS) IANA Considerations. September 2000.
[RFC1033] Domain administrators operations guide. November 1987.
[RFC1537] Common DNS Data File
Configuration Errors. October 1993.
[RFC1912] Common DNS Operational and
Configuration Errors. February 1996.
[RFC2010] Operational Criteria for Root Name Servers. October 1996.
[RFC2219] Use of DNS Aliases for
Network Services. October 1997.
A Common Operational Problem in DNS Servers: Failure to Communicate
. September 2020.
Internationalized Domain Names
[RFC2825] A Tangled Web: Issues of I18N, Domain Names,
and the Other Internet protocols. May 2000.
[RFC3490] Internationalizing Domain Names in Applications (IDNA). March 2003.
[RFC3491] Nameprep: A Stringprep Profile for Internationalized Domain Names. March 2003.
[RFC3492] Punycode: A Bootstring encoding of Unicode
for Internationalized Domain Names in
Applications (IDNA). March 2003.
Other DNS-related RFCs
Note: the following list of RFCs, although
DNS-related, are not
concerned with implementing software.
[RFC1464] Using the Domain Name System To Store Arbitrary String
Attributes. May 1993.
[RFC1713] Tools for DNS Debugging. November 1994.
[RFC1794] DNS Support for Load
Balancing. April 1995.
[RFC2240] A Legal Basis for Domain Name Allocation. November 1997.
[RFC2345] Domain Names and Company Name Retrieval. May 1998.
[RFC2352] A Convention For Using Legal Names as Domain Names. May 1998.
[RFC3071] Reflections on the DNS, RFC 1591, and Categories of Domains. February 2001.
[RFC3258] Distributing Authoritative Name Servers via
Shared Unicast Addresses. April 2002.
[RFC3901] DNS IPv6 Transport Operational Guidelines. September 2004.
Obsolete and Unimplemented Experimental RFC
[RFC1712] DNS Encoding of Geographical
Location. November 1994.
[RFC2673] Binary Labels in the Domain Name System. August 1999.
[RFC2874] DNS Extensions to Support IPv6 Address Aggregation
and Renumbering. July 2000.
Obsoleted DNS Security RFCs
Most of these have been consolidated into RFC4033,
RFC4034 and RFC4035 which collectively describe DNSSECbis.
[RFC2065] Domain Name System Security Extensions. January 1997.
[RFC2137] Secure Domain Name System Dynamic Update. April 1997.
[RFC2535] Domain Name System Security Extensions. March 1999.
[RFC3008] Domain Name System Security (DNSSEC)
Signing Authority. November 2000.
[RFC3090] DNS Security Extension Clarification on Zone Status. March 2001.
[RFC3445] Limiting the Scope of the KEY Resource Record (RR). December 2002.
[RFC3655] Redefinition of DNS Authenticated Data (AD) bit. November 2003.
[RFC3658] Delegation Signer (DS) Resource Record (RR). December 2003.
[RFC3755] Legacy Resolver Compatibility for Delegation Signer (DS). May 2004.
[RFC3757] Domain Name System KEY (DNSKEY) Resource Record
(RR) Secure Entry Point (SEP) Flag. April 2004.
[RFC3845] DNS Security (DNSSEC) NextSECure (NSEC) RDATA Format. August 2004.
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
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
DNS and BIND. Copyright © 1998 Sebastopol, CA: O'Reilly and Associates.