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Add static entry to linux dns server

Posted on 2008-11-04
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I have a bind9 dns server on Ubuntu 8.10. I want to add a static domain to the server for testing. The test domain we will say is company.com. This domain is external from the network i am in. I already have the local zone set up and working.

I am doing this because this company randomly has email fail to a certain domain. It works fine for weeks and the it just stops working and returns 550 host unknow company.com.  

What i want to do is add the mx records for company.com statically in the dns server for testing.  

This only started after these guys started trendmicro's IMHS service, if that helps. .

Thanks
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Question by:bml104
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Hugh Fraser earned 750 total points
ID: 22882026
The basic IMHS service hosts inbound mail only through an MX record, so it wouldn't affect outbound mail. You need to check if you have this or their advanced service which checks outbound mail as well (I'm getting this from their web site). If it's the latter, they should be doing the resolving, not you.

Assuming you;re delivering outbound mail yourself, adding another site's MX records (and implicitly their entire domain to get the MX records to resolve) is a bad idea, since there's no mechanism to recognize when they make changes. You need to resolve the DNS issues.

You could start by using one of many online DNS check services like http://www.intodns.com to see if it reports any errors.

You'll also need to check the status of your internal DNS (which is forwarding the requests) at the time email fails.
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by:bml104
ID: 22885357
I agree, fix the DNS is the same solution I came up with. I totally understand that adding a static entry can cause problems in the wrong run when change occurs. However, this is a customer we setup on the Trend servers. They never saw the problem until we implemented the Trend solution. So the problem is because of what we did and not an issue with their internal Bind server, in their eyes that is.

I sat on the phone with the admin and had him do an nslookup and dig mx when email was failing. The both showed the resolution was failing at his internal server.The problem is it only happens every few days. It will work fine for 5 days with no issues. Then one day it will send back 550 host not found and the messages will never deliver. 15 min later everything is working fine again.




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by:bml104
ID: 22885575
It seems that their issue is trendmicro's mx records point to cnames and some dns servers do not like this.

http://exchangepedia.com/blog/2006/12/should-mx-record-point-to-cname-records.html

I guess their is a battle between trend and everyone else. Everyone knows what the problem is but provides no solution. Anyone here have any ideas how to fix it?

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by:jcs5003
ID: 22890424
Use another email filtering / av service. MX Logic is a good choice.
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by:Hugh Fraser
ID: 22890939
It certainly seems that everyone (including the following article from Microsoft) agrees that MX records pointing to a CNAME are a bad practice, although it's not clear if it violates standards.

http://support.microsoft.com/kb/153001

Regardless, I'd be worried about an email service that uses an addressing technique that many people caution against. TrendMicro's stance that they adhere to changes to the standard isn't much comfort if others do not. I'd be taking it up with them or switching services as well.
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by:bml104
ID: 22894873
hfraser,
Your post pointed me to intodns.com which pointed out some interesting errors I pointed out above. I have implemented the fix trend suggested and will post it as soon as I know it works. It might take a week to make sure no emails are lost. When the fix is proven I will award you the points for pointing me in the right direction.


THanks
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