Null MX

Null MX

The Null MX proposal is a way of saying that "this domain name never accepts e-mail" via MX records. It is specified in the now expired internet draft [http://tools.ietf.org/html/draft-delany-nullmx draft-delany-nullmx] from 2005.

The proposal uses an MX record in the DNS with a priority of zero and a host name of ".", such as:

example.com. MX 0 .

When an SMTP server attempts to send mail to a domain with a Null MX record, the server will find that the domain name supposed to handle e-mail is ".", which is the root name server. Servers will then attempt to look up the IP address for the root name server and then connect to a mail server. As of 2008, there are currently no A nor AAAA records for the root name servers so the delivery will fail. E-mail servers that follow this specification can short-circuit this lookup and stop the delivery immediately; however, that is making the assumption that the root name servers will never have A/AAAA records, something that has not been guaranteed.

Note that a "this domain can not receive e-mail" policy is not the same as policies that can be specified by DomainKeys and SPF that say "this domain does not send e-mail". Some systems will reject e-mail from systems that can not receive e-mail back, but many do not.

Criticisms

Since, by default, this proposal causes additional load on the root name servers, it has not been well received on the IETF DNSEXT working group [ [http://www.ops.ietf.org/lists/namedroppers/namedroppers.2005/msg00939.html draft-delany-nullmx-00.txt good? bad? ugly?] ]

References


Wikimedia Foundation. 2010.

Игры ⚽ Нужна курсовая?

Look at other dictionaries:

  • Null — (de) …   Kölsch Dialekt Lexikon

  • null —  null …   Hochdeutsch - Plautdietsch Wörterbuch

  • Null —  Pour le musicien japonais, voir Kazuyuki K. Null. NULL est un mot clef présent dans de nombreux langages informatiques, et qui désigne l état d un pointeur qui n a pas de cible ou d une variable qui n a pas de valeur. La notion de valeur ou …   Wikipédia en Français

  • Null — may refer to: Contents 1 In computing 2 In art 3 In mathematics 4 In science 5 People …   Wikipedia

  • Null — «Null» redirige aquí. Para otras acepciones, véase Null (desambiguación). El término null o nulo es a menudo utilizado en la computación, haciendo referencia a la nada. En programación, null resulta ser un valor especial aplicado a un puntero (o… …   Wikipedia Español

  • null — [nʌl] adjective [only before a noun] 1. STATISTICS a null effect, result etc is one that is zero or nothing 2. LAW another name for null and void: • Their suit also asks the court to declare null the buyer s shareholder rights plan. * * * …   Financial and business terms

  • NULL (Си и Си++) — NULL в языках программирования Си и C++  макрос, объявленный в заголовочном файле stddef.h (и других заголовочных файлах). Значением этого макроса является зависящая от реализации константа нулевого указателя (англ. null pointer constant).… …   Википедия

  • null — / nəl/ adj [Anglo French nul, literally, not any, from Latin nullus, from ne not + ullus any]: having no legal or binding force: void a null contract Merriam Webster’s Dictionary of Law. Merriam Webster. 1996 …   Law dictionary

  • Null — Null, a. [L. nullus not any, none; ne not + ullus any, a dim. of unus one; cf. F. nul. See {No}, and {One}, and cf. {None}.] 1. Of no legal or binding force or validity; of no efficacy; invalid; void; nugatory; useless. [1913 Webster] Faultily… …   The Collaborative International Dictionary of English

  • Null-O — is a 1958 science fiction short story by Philip K. Dick. This rather brief story examines the concept of totally unempathic and logical humans ( Null O s) in an obvious parody of the plot and concepts of The Players of Null A by A. E. van Vogt.… …   Wikipedia

  • Null — Sf std. (16. Jh.) Entlehnung. Entlehnt aus l. nulla gleicher Bedeutung, feminine Substantivierung von l. nullus keiner . Dieses ist eine Lehnbedeutung von arab. ṣifr, das ebenfalls Null und leer bedeutet und das seinerseits ai. śūnya Null, leer… …   Etymologisches Wörterbuch der deutschen sprache

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”