Suggested DNS records showing IP4 twice. Why?

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#1 Sat, 12/21/2019 - 02:27
adamjedgar

Suggested DNS records showing IP4 twice. Why?

below is an example of Virtualmin>Server Configuration> Suggested DNS Records

domain.com. IN A 12.34.56.78
www.domain.com. IN A 12.34.56.78
ftp.domain.com. IN A 12.34.56.78
m.domain.com. IN A 12.34.56.78
localhost.domain.com. IN A 127.0.0.1
webmail.domain.com. IN A 12.34.56.78
admin.domain.com. IN A 12.34.56.78
mail.domain.com. IN A 12.34.56.78
domain.com. IN MX 5 mail.domain.com.
domain.com. IN TXT "v=spf1 a mx a:domain.com ip4:12.34.56.78 ip4:12.34.56.78 ?all"


  1. why is it showing the IP4 address twice?

  2. also, why is MXrecord value "mail.domain.com" being suggested when there is no mail server on the system with this hostname? The webmin host doesnt even use that name (its one of the clients/virtual servers...these are not real servers), so why is this being suggested in Virtualmin? Shouldnt virtualmin be using the actual system hostname.fqdn when suggesting dns records?

Sat, 12/21/2019 - 09:43
Dibs

I think there must be a bug that's causing the SPF record to show the ip4 address twice.

mail.domain.com is an alias that is automatically added when you enable mail for a domain (I think).

Sat, 12/21/2019 - 15:13
adamjedgar

But where is that alias actually stored on system? I don't see it anywhere (maybe I am looking in wrong place)

Also, for postfix, does an alias even work as a sender when it's not a real domain?

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Sun, 12/22/2019 - 17:25
Dibs

I think Postfix accepts mail for all sub domains for a domain (with mail enabled). Suggesting mail.domain.com as a DNS record might just be something that's become the norm - you could test it by making it mails.domain.com as a test and see if mail inbound & outbound works - I suspect it will.

Postfix uses entries in /etc/Postfix/virtual (which is subsequently hashed) to work out what domains to receive mail for.

HIH

Dibs

Sun, 12/22/2019 - 18:26
NicholasChua

Hi Dibs,

Out of point. I am not using Postfix

Thanks nic

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