Mailinglist Archive: opensuse (878 mails)

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Re: [opensuse] Is it possible to send email with postfix without DNS?
  • From: Werner Flamme <werner.flamme@xxxxxxxx>
  • Date: Sun, 01 Sep 2013 07:47:23 +0200
  • Message-id: <5222D4EB.40905@email.de>
[01.09.2013 03:31] [Carlos E. R.]:


On Saturday, 2013-08-31 at 18:36 -0400, James Knott wrote:
Carlos E. R. wrote:
/etc/resolv.conf:

search valinor #nameserver 192.168.1.1 nameserver 127.0.0.1

I use the external DNS servers here. I have 3 of them, 2 IPv6 and
1 IPv4.

/etc/dnsmasq.conf:

server=192.168.1.1

On my system, that line is commented out.

The documentation says that the way you say it works for other
machines asking this machine for names.

But if you want the machine running dnsmasq to also query its own
dnsmasq, it says that you point nameserver to itself in resolv.conf,
and to an external place in dnsmasq.conf.

If you don't do the second part, you get a loop and no external
resolution, which is the problem I had two posts ago.

So, if in resolv.conf you have several external DNS, and in
dnsmasq.conf the "server=" is commented out, then that machine sends
all queries to outside, not asking its own dnsmasq. Your local
network machines instead can ask that machine dnsmasq.


That is the way it is run on my 20+ SAP systems at the office.
resolv.conf may point to 1-3 nameservers, and so I configured 127.0.0.1
first, followed by two company name servers as failover when the local
dnsmasq is not reachable. But only the local DNSmasq knows all about
internally used hostnames in the SAP landscape, which often differ from
the "official" ones.

In dnsmasq.conf, I define all company name servers on one server= line
each, and I tell dnsmasq "no-resolv", because that would be a recursion ;-)

BTW, I also use "no-negcache", because sometimes the main internal DNS
cluster has a hiccup... In case of mail, this may result in a deferred
mail, mails warning you that the mail is deferred (being deferred
themselves), and so on - from one mail sent you get 5 mails delivered at
least ;-)

Regards,
Werner
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