Solved

DNS issues with sendmail

Posted on 2004-09-27
10
233 Views
Last Modified: 2010-04-20
Hi ee,  I have a linux server running sendmail for about 40 users.  I have branch offices connected via dsl and a head office via international leased line.  All my branch offices have local mail accounts on my server .  This server sends mail and receives via my head office.  The dns server is the ip at my head office.  My problem is this, when my link goes down (head office)  no mail goes out .  This i understand.  But even local mail doesnt get delivered.  Is there anyway to make it possible for my local mail to be delivered when the link is down to my head office?
0
Comment
Question by:aduhwale
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 5
  • 2
  • 2
  • +1
10 Comments
 
LVL 6

Expert Comment

by:de2Zotjes
ID: 12161697
You can add an extra service to your linux server. You could have it run a dns-server, if you configure this dns to be a secondary nameserver for your own (internal) domains then mail delivery to local accounts should be able to continue if the link is down.

It is a good idea to do this anyway, because the nameserver will cache info that it looked up, so the load on the leased line will go down if you run a dns-server at your site.
0
 
LVL 3

Expert Comment

by:ChrisEddy
ID: 12165855
Adding to the previous comment, but with respect to the modest number of mail sending users, keep an eye on memory consumption by both the DNS (eg: bind as a cache) and the number of sendmail processes.  Bind can be configured to limit memory consumption to a maximum.  Remember to modify the DNS lookup sequence in /etc/resolv.conf, and send a SIGHUP to the name daemon to reread the new configuration.  

Architecturally, you may prefer to have a box dedicated to serving DNS, since it limits memory growth and context switches to that box, and can limit the number of people who can or need to administer the box (people * change = risk = bad).

Another tidbit of information that you might find interesting is a cacheing subsustem called Squid, which handles DNS, HTTP, and some other things that can benefit performance by being cached.   See: http://www.squid-cache.org/
0
 
LVL 2

Author Comment

by:aduhwale
ID: 12166822
Hi guys, thanks for your responses.  I went into webmin to look at creating a dns server and was blown away by the number of options.  What is the easy way to setting this up?
0
Windows Server 2016: All you need to know

Learn about Hyper-V features that increase functionality and usability of Microsoft Windows Server 2016. Also, throughout this eBook, you’ll find some basic PowerShell examples that will help you leverage the scripts in your environments!

 
LVL 3

Expert Comment

by:ChrisEddy
ID: 12170308
You didn't mention which Linux you're using...

On my Redhat 7.3 system using Gnome, there's a configuration for defining local zones:
programs -> system -> DNS Configuration

However, you might be better served by information from the Internet Systems Consortium, which publishes the BIND name server.  Sometimes it's just easier to start with a standard cacheing DNS configuration and manually add the information for your local site to a new zone that is served by the cache.
http://www.isc.org/index.pl?/sw/bind/contributions.php

0
 
LVL 2

Author Comment

by:aduhwale
ID: 12177410
Hi.  again ,  I am using fedora core 2
0
 
LVL 2

Author Comment

by:aduhwale
ID: 12237579
Hi guys, still looking for  a simple  solution to dns woes.
0
 

Accepted Solution

by:
viznogoud earned 350 total points
ID: 12282513
check if the line:
MAILER(local)dnl
is in your sendmail.mc file.
If not, add it and rebuild sendmail.mc.
0
 
LVL 2

Author Comment

by:aduhwale
ID: 12284205
Hi there.  I added this and then rebuilt sendmail.mc .  It would appear I was using some configuration that I hadnt rebuilt?  coz now my secondary mail server  (602 lansuit) is unable to send via this server,  I can pick pop mail from it but it rejects the smtp connections,  I took out the change I made to add mailer(local) dnl in case it was the cause but same thing.       I guess I forgot to save before I made these changes.  Add idea why sendmail will reject smtp connections from my secondary mail server?

0
 
LVL 2

Author Comment

by:aduhwale
ID: 12286857
Hi again.  I saw what I messed up,  it is now fixed and the solution above has worked!

Thanks
0
 

Expert Comment

by:viznogoud
ID: 12293093
Great, glad to be of help.
0

Featured Post

NEW Veeam Agent for Microsoft Windows

Backup and recover physical and cloud-based servers and workstations, as well as endpoint devices that belong to remote users. Avoid downtime and data loss quickly and easily for Windows-based physical or public cloud-based workloads!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Suggested Solutions

Title # Comments Views Activity
Remote desktop Ubuntu from Windows 10 5 128
winscp where are logs stored 3 75
Migrating a Linux server to VMware 3 112
regular expression help for sed command 5 42
I am a long time windows user and for me it is normal to have spaces in directory and file names. Changing to Linux I found myself frustrated when I moved my windows data over to my new Linux computer. The problem occurs when at the command line.…
Introduction We as admins face situation where we need to redirect websites to another. This may be required as a part of an upgrade keeping the old URL but website should be served from new URL. This document would brief you on different ways ca…
Learn how to find files with the shell using the find and locate commands. Use locate to find a needle in a haystack.: With locate, check if the file still exists.: Use find to get the actual location of the file.:
Connecting to an Amazon Linux EC2 Instance from Windows Using PuTTY.

726 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question