Using the Domain Name System To Store Arbitrary String Attributes (RFC1464)
Original Publication Date: 1993-May-01
Included in the Prior Art Database: 2000-Sep-12
Internet Society Requests For Comment (RFCs)
While the Domain Name System (DNS) [2,3] is generally used to store predefined types of information (e.g., addresses of hosts), it is possible to use it to store information that has not been previously classified.
Network Working Group R. Rosenbaum
Request for Comments: 1464 Digital Equipment Corporation
Using the Domain Name System
To Store Arbitrary String Attributes
Status of this Memo
This memo defines an Experimental Protocol for the Internet
community. Discussion and suggestions for improvement are requested.
Please refer to the current edition of the "IAB Official Protocol
Standards" for the standardization state and status of this protocol.
Distribution of this memo is unlimited.
While the Domain Name System (DNS) [2,3] is generally used to store
predefined types of information (e.g., addresses of hosts), it is
possible to use it to store information that has not been previously
This paper describes a simple means to associate arbitrary string
information (ASCII text) with attributes that have not been defined
by the DNS. It uses DNS TXT resource records to store the
information. It requires no change to current DNS implementations.
The Domain Name System is designed to store information that has both
a predefined type and structure. Examples include IP addresses of
hosts and names of mail exchangers. It would be useful to take
advantage of the widespread use and scaleability of the DNS to store
information that has not been previously defined.
This paper proposes the use of the DNS TXT resource record (defined
in STD 13, RFC 1035) to contain new types of information. The
principal advantage of such an approach is that it requires no change
to most existing DNS servers. It is not intended to replace the
process by which new resource records are defined and implemented.
2. Format of TXT record
To store new types of information, the TXT record uses a structured
format in its TXT-DATA field. The format consists of the attribute
name followed by the value of the attribute. The name and value are
separated by an equals sign (=).
For example, the following TXT records contain attributes specified
in this fashion:
host.widgets.com IN TXT "printer=lpr5"
sam.widgets.com IN TXT "favorite drink=orange juice"
The general syntax is:
Any printable ASCII character is permitted for the attribute name.
If an equals sign is embedded in the attribute name, it must be
quoted with a preceding grave accent (or backquote: "`"). A
backquote must also be quoted with an additional "`".
Attribute Name Matching Rules
The attribute name is considered case-insensitive. For example, a
lookup of the attribute "Favorite Drink" would match a TXT record
containing "favorite drink=Earl Grey tea".
During lookups, TXT records that do not contain an unquoted "=" are
ignored. TXT records tha...