(RFC 4027 published April 2005, subtype last updated April 2005) MIME media type name: text MIME subtype name: dns Required parameters: None. Optional parameters: None. Encoding considerations: The data is textual and should be transfered in a line-oriented mode. Text literals may contain CRLF within the text. Binary transport 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 by 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-encodes the character data. Security considerations: This media type identifies content as being DNS information in "master file" format, as documented in RFC 1035 [2]. The DNS data may be security relevant as per to RFC 2538 [7], or may be secured information as per to RFC 2535 [6]. Securing the content further may be done with standard techniques, such as OpenPGP [5] or CMS [9], 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 widespread use of vendor-specific extensions. Non-ASCII comments within master files may have been encoded in locally chosen character sets, which may be difficult to transport interoperably. Non-ASCII data in general can become corrupted by re-encoding gateways. To achieve interoperability, one can use the master file format described in the specification and the "\DDD" encoding for non-ASCII octets. Further interoperability issues with unrecognized RR types exist, which may be handled as discussed in section 5 of RFC 3597 [8]. Published specification: The format of data that could be tagged with this MIME type is documented in RFC 1035 [2]. Applications that 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