Oddball DNS issue: won't resolve hostname alone.

Charles Curley charlescurley at charlescurley.com
Thu Dec 20 10:29:39 MST 2007


On Mon, Dec 17, 2007 at 11:19:10PM -0700, Shane Hathaway wrote:
> Charles Curley wrote:
> > Postfix *is* supposed to relay. The postfix instance is running on
> > phoenix, and the mail is addressed to root, which phoenix has aliased
> > as ccurley at charlesc.
> 
> Ah, ok.  Some thoughts:
> 
> - You might be able avoid the issue by changing the root alias to point
> to 'ccurley at charlesc.localdomain' instead.
> 
> - AFAIK Postfix does not consult resolv.conf; it talks to DNS directly.

Oh. How does it find a name server to talk to without
/etc/resolv.conf?

> 
> - See 'man 5 postconf' for reference.
> 
> - Use 'postconf | less' to see the current config values.
> 
> - The Postfix 'mydomain' parameter should be set to 'localdomain'.

root at phoenix:~# postconf | grep mydomain
append_dot_mydomain = no
mydomain = localdomain


> You can use the 'dnsdomainname' command to find out what the machine
> thinks its domain name is.  The way to change the domain name
> persistently varies by distribution.

root at phoenix:~# dnsdomainname
root at phoenix:~# 

This is on ubuntu 7.10.

I also have a name server on charlesc, Fedora Core 7, which I am
trying to phase out. When I run it, the mail system works. When I
don't, the mail system breaks.

This may be related to the fact that when I set phoenix up, charlesc
was the main DNS and everything else server.

> 
> - Setting up MX records isn't hard and may pay off in stability.

So I need an MX record as well as an A name for each machine? Yucch.

> 
> - If you must, you can short-circuit the whole name lookup using a
> transport map.  See the 'transport_maps' Postfix parameter.
> However, while transport maps are powerful, this sort of hack
> shouldn't be necessary.

I have or have had working sendmail systems. Maybe I should just put
sendmail on all my Ubuntu machines.

-- 

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