Domain Name System Media Types

Domain Name System (DNS) information is traditionally stored in text files, so called master files or zone files. The format is described in section 5 of RFC 1035 . DNS data can also be stored in a "detached" format, intended for archiving purposes, described in RFC 2540 . This document register MIME media types for the two data formats, following the registration procedures described in RFC 2048 .

To: ietf-types@iana.org Subject: Registration of MIME media type application/dns MIME media type name: application MIME subtype name: dns Required parameters: None. Optional parameters: None. Encoding considerations: The data format is binary, and data must be transfered unmodified. Using encodings intended for textual parts is not recommended. Security considerations: This media type identify content as being detached DNS information, as documented in RFC 2540 . This data may be security relevant according to RFC 2538 , or secured information according to RFC 2535 . Securing the content further may be done by standard techniques, such as OpenPGP or CMS , but this is outside of the scope here. Further security assessments are not available at this point. Interoperability considerations: The encoding of detached DNS information is, unlike textual master files, well defined. No further interoperability considerations are known. Published specification: The format of data that could be tagged with this media type is documented in RFC 2540 . Applications which use this media type: DNS related software, including software storing and using certificates stored in DNS.

Additional information: Magic number(s): None. File extension(s): Unknown. Macintosh File Type Code(s): Unknown. Person & email address to contact for further information: Simon Josefsson simon@josefsson.org Intended usage: LIMITED USE Author/Change controller: simon@josefsson.org

To: ietf-types@iana.org Subject: Registration of MIME media type text/dns MIME media type name: text MIME subtype name: dns Required parameters: None. Optional parameters: None. Encoding considerations: The data is textual, and should be transferred in a line oriented mode. Text literals may contain CRLF within the text. Binary transports is possible between systems that use the same end-of-line conventions. Master files are in general ASCII, but non-ASCII octet values may occur and are treated as opaque values by DNS software (compare RFC 1035 section 5). The master file format permits encoding arbitrary octet values using the "\DDD" encoding. The use of "\DDD" encoding can be more reliable than transporting non-ASCII through MIME transports, if data passes through a gateway that re-encode the character data. Security considerations: This media type identify content as being DNS information in "master file" format, as documented in RFC 1035 . The DNS data may be security relevant according to RFC 2538 , or secured information according to RFC 2535 . Securing the content further may be done by standard techniques, such as OpenPGP or CMS , but this is outside of the scope here. Further security assessments are not available at this point. Interoperability considerations: There are interoperability concerns with master files, due to the wide spread use of vendor specific extensions. Non-ASCII comments within master files may have been encoded in a locally chosen character sets, that can be difficult to transport interoperable. Non-ASCII data in general can become corrupted by re-encoding gateways. To achieve interoperability, you can use the master file format described in the specification and the "\DDD" encoding for non-ASCII octets. Published specification: The format of data that could be tagged with this MIME type is documented in RFC 1035 . Applications which use this media type: DNS related software, including software storing and using certificates stored in DNS.

Additional information: Magic number(s): None. File extension(s): 'soa' and 'zone' are known to be used. Macintosh File Type Code(s): Unknown. Person & email address to contact for further information: Simon Josefsson simon@josefsson.org Intended usage: LIMITED USE Author/Change controller: simon@josefsson.org

Security considerations are discussed in the security considerations clause of the MIME registrations in section 2 and 3.

The IANA is asked to register the MIME media types application/dns and text/dns using the registration templates in section 2 and 3, according to the procedure described in RFC 2048 .

Thanks to D. Eastlake for suggesting text/dns. Thanks to Keith Moore for reviewing earlier versions of this document. The author acknowledges the RSA Laboratories for supporting the work that led to this document.