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Exchange 2010 outgoing emails with error 451.4.4.0 DNS Query Failed

Hi Experts,

Please reply how to configure DNS internally and externally on sbs 2011, do i need to add the forwarders on it, please provide steps to configure the DNS so that all outgoing emails will not get any errors like i am getting 451.4.4.0 on Queue viewer...as emails are going via dns mx records but not from Smart Hosts.

It is new sbs 2011 where 9 users working.

Thanks.
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6300ac
Asked:
6300ac
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1 Solution
 
James HIT DirectorCommented:
Can you restart the DNS Server service and see if that doesn't resolve this issue.
Typically Exchange uses root hints and not forwarders.
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hax1Commented:
Hi,

if your sbs is configured to use itself as DNS Server (which I assume is the case), then you need to add forwarders -> simply open dns manager -> right click on your server -> go to properties and forwarders -> add f.e. 8.8.8.8 and 8.8.4.4 (google public dns) and everything should work fine. make sure the ip address you use has a reverse hostname assigned to it, otherwise you might have trouble delivering e-mail, or use an external smtp connector to deliver mail (which is preferred if you have a non-business-line internet access).

see: http://jing.hax.at/2011-10-04_1444.png (in german though)

best regards
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6300acAuthor Commented:
did what you told me, restarted the services but not any good..i add 8.8.8. on sbs 2011 as seconday dns address on(adaptor settings)
lets see if that works..still not tested..
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hax1Commented:
also try:

- open a command prompt
- nslookup
- set type=mx
- domain.com. (don't forgot the dot)

and see if that works.

problem is probably that you have set the server itself as a forwarder, which then won't work ...
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RadweldCommented:
The DNS server on your SBS needs to be functioning in order for Exchange to deliver mail because when you email someone@domain.com, Exchange uses DNS to locate the MX record for domain.com then initiates a point to point connection to deliver the mail. If no MX record is identified then Exchange will be unable to deliver the mail.

So you need to ensure you perform the texts HAX1 posted above, ensure that the domains who are not receiving mail can be located using the nslookup diagnostics tool.

I have seen several similar issues in the past caused by a defective root hint, if your using external forwarders which you say you have now setup, you no longer need root hints and if you have both configured sometimes this can lead to problems obtaining the correct data.

I think your issue is pretty much an DNS problem and you can also clear down the DNS cache in case you have stale records.
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hax1Commented:
ipconfig /flushdns from the command prompt flushes dns records, however shouldn't be necessary since it should always look up addresses it couldn't resolve before anyway ...
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RadweldCommented:
IPconfig /FlushDNS clears the client cache, not the server cache.

To clear the server cache you need to execute from the command prompt,

Dnscmd ServerName /clearcache

Stale records in your cache can cause exactly this kind of problem and should not be confused with the client side resolve cache.
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6300acAuthor Commented:
Problem solved as i setup new secondary dns address 8.8.8.8 on server lan adaptor.
Thank you all for help.

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Computer HelperWindows Server AdminCommented:
I had to do everything in this post to solve my issue.  Using google DNS in the forwarders helped but didn't clear the entire exchange que.  I had to turn off root hints, clear dns cache, and add google DNS as a secondary DNS on my NIC settings (IPV4)
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