Path: utzoo!mnetor!tmsoft!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!uwm.edu!ux1.cso.uiuc.edu!mp.cs.niu.edu!rickert
From: rickert@mp.cs.niu.edu (Neil Rickert)
Newsgroups: comp.mail.sendmail
Subject: Re: sendmail & nameservice
Message-ID: <1990Dec21.151917.19298@mp.cs.niu.edu>
Date: 21 Dec 90 15:19:17 GMT
References: <1990Dec21.121210.17836@turnkey.tcc.com>
Organization: Northern Illinois University
Lines: 43

In article <1990Dec21.121210.17836@turnkey.tcc.com> jackv@turnkey.TCC.COM (Jack F. Vogel) writes:
>Can someone tell me why sendmail is coded to be "all or nothing", as it were,
>dependent on the nameserver? What I mean is that the way things are set up,
<(...)
>falls back to parsing the host file. Can someone tell me, particularly other
>vendors, how you handle this dichotomy? As things stand if I compile with

  Well, I am not another vendor.  My observation is that many vendors ship
two versions of 'sendmail' with their software.  They call one 'sendmail'
and the other 'sendmail.mx'.

  I like the idea of two version, but I think they do it wrongly.  They
should ship one as 'sendmail.mx' and the other as 'sendmail.nomx'  Then
they should install a link from 'sendmail' to 'sendmail.nomx' in their
default setup.  Preferably a symbolic link should be used if the system
supports it.  This approach makes it easier to see which mailer is being
used, and reduces the risk of inadvertently deleting on.

  For systems that use NFS and diskless workstations, they should go
one step further:  make '/usr/lib/sendmail' a symbolic link to '/etc/sendmail',
and make '/etc/sendmail' a symbolic link to either '/usr/lib/sendmail.nomx'.
This of course sounds very complex, but it allows the main server to use
'sendmail.mx' and the diskless workstation to use 'sendmail.nomx' while
at the same time both share a common '/usr' partition.

>NAMED_BIND defined that binary fails for someone not using a nameserver. I
>am considering altering getcanonname() to fall back on the host file, but
>I was wondering whether there was something I was missing?? Has no-one run

  The problem with this approach is that it makes mail unreliable.  At present
if you are using an MX mailer, and the network link temporarily fails, the
messages go into the queue due to nameserver lookup failure.  With your
approach during network failures the messages affected will all be bounced with
'Unknown host'.  If using a nameserver, make your host a secondary name server
(even if unofficial) for the local domain, using a nameserver such as
4.8.3 which makes a disk copy of the domain data.  That way local mail can
still be delivered even when there is a network failure.

-- 
=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=*=
  Neil W. Rickert, Computer Science               <rickert@cs.niu.edu>
  Northern Illinois Univ.
  DeKalb, IL 60115                                   +1-815-753-6940