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postfix-users: Re: is this DNS setup RFC-correct ?

Re: is this DNS setup RFC-correct ?

From: Bastian Blank <bastian+postfix-users=postfix.org_at_nospam>
Date: Thu Oct 28 2010 - 15:24:40 GMT
To: postfix-users@postfix.org

On Mon, Oct 25, 2010 at 02:20:51PM -0200, Leonardo Rodrigues wrote:
> nnn.domain.com.br (about 40 different subdomains) have only 2 (two)
> DNS entries:
>
> nnn IN MX 10 server.nnn.domain.com.br.
> nnn IN TXT "v=spf1 include:domain.com.br -all"

| ;; ->>HEADER<<- opcode: QUERY, status: NXDOMAIN, id: 65089
| ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
|
| ;; QUESTION SECTION:
| ;nnn.domain.com.br. IN ANY

Nope, nnn.domain.com.br does not exist at all.

> i really dont know if this setup (MX record but no A record) is
> RFC-OK. The only think i know is that it's been working for years and i
> receive thousand of emails daily on my several subdomains with no
> problem at all.

It is. See RFC 821, 5321.

> question is .... do a domain (or in my case, a subdomain) *MUST*
> have an A record ? Is the config i'm doing (DNS speaking) correct or
> incorrect (RFC-speaking) ??

No. The name listed in the MX record may also only have AAAA for
example.

Bastian

-- What kind of love is that? Not to be loved; never to have shown love. -- Commissioner Nancy Hedford, "Metamorphosis", stardate 3219.8