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Exchange 2013 - DnsConnectorDelivery 451 4.4.0 DNS Query Failed

Posted on 2015-01-28
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Last Modified: 2015-02-06
Exchange server is running Windows 2012. Single Server.
DC/DNS server is running Windows 2012R2.  DNS uses our router for lookups.

I have to start saying, i started to experience these issues after upgrading from my old DC(2003) to 2012R2.

Most email has no issues sending, tho it seems domains that are hosted by google/gmail, have issues.  The email either send quickly as normal or will take a few rehours to send out. A few hours have gotten the "you email has been delayed", which i have set to 4 hours.  

I keeping getting this error: DnsConnectorDelivery 451 4.4.0 DNS Query Failed. The Error was: DNS Query failed with ErrorTimeout.

The current domain that is causing issues is eastonsd.org. i have no problems with nslookup on the exchange server, results below.

S:\>nslookup
Default Server:  bsddc.local
Address:  192.168.0.5

> set q=mx
> eastonsd.org
Server:  bsddc.local
Address:  192.168.0.5

Non-authoritative answer:
eastonsd.org    MX preference = 20, mail exchanger = ALT1.ASPMX.L.GOOGLE.COM
eastonsd.org    MX preference = 20, mail exchanger = ALT2.ASPMX.L.GOOGLE.COM
eastonsd.org    MX preference = 30, mail exchanger = ASPMX2.GOOGLEMAIL.COM
eastonsd.org    MX preference = 10, mail exchanger = ASPMX.L.GOOGLE.COM
eastonsd.org    MX preference = 30, mail exchanger = ASPMX4.GOOGLEMAIL.COM
eastonsd.org    MX preference = 30, mail exchanger = ASPMX5.GOOGLEMAIL.COM
eastonsd.org    MX preference = 30, mail exchanger = ASPMX3.GOOGLEMAIL.COM
>
S:\>nslookup eastonsd.org
Server:  bsddc.local
Address:  192.168.0.5

Non-authoritative answer:
Name:    eastonsd.org
Address:  66.246.215.161

whats my next step? after googling a bunch of different fixes, most seem to be for exchange 2007/2010. i'm currently not using any external dns lookups in exchange config.
dns.png
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Question by:AfternoonShift
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Accepted Solution

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AfternoonShift earned 0 total points
ID: 40576570
OK.

i just made one change...  i checked "Use the external DNS look settings on servers with transport roles" and the emails sent.
i'll attach screenshot for location...

I'm not sure why all of a sudden i need to check this, but seems to work. Would still love to hear some feedback with anyone else that had this same issue.
send.png
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LVL 6

Expert Comment

by:JeffG2583
ID: 40576669
Could it be the DNS cache on your router got corrupted? I've had to clear cache on Win 2008 servers to fix similar issues. Just a thought.
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LVL 11

Expert Comment

by:Tej Pratap Shukla ~Dexter
ID: 40576679
hi..

Nice to listen from you that you have solved your query...

Whenever a user tries to send email an error with the message 451 “4.4.0 DNS Query Failed” pops up.

Generally this happens due to the misconfiguration or if we have booked the recipient domain.

Use the External DNS Lookup settings on the transport server

By default Exchange will use internal DNS servers - what is configured on the network card of the server.
This setting allows you to specify different external servers for Exchange to use instead of the local ones. They are used for transport only, so shouldn't affect the operation of the server for DNS.

However the setting is not used that often, and in most cases is not required.

Thanks
Dexter
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Author Closing Comment

by:AfternoonShift
ID: 40593216
After clicking this option, email has been working without issues.
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