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Error 451 Dns Query Failed

    Question

  • Hi,

    It's been a while since I seek why it does not work, but still nothin, so I come to ask your help please.

    Currently I can send email internally and externally.
    But impossible to receive from the outside, I get that error on Edge :

    exchange.internal.domain / SmartHostConnectorDelivery / Error 451 DNS Query Failed. SMTPSEND.DNS.NonExistentDomain; nonexistantdomain

    Here are my configurations

    - AD local only

    - Exchange
    ETH0: lan (dns to AD)
    ETH1: wan (dns 8.8.8.8)

    - Edge Transport
    ETH0: lan (dns to AD)
    ETH1: wan (dns 8.8.8.8)
    HOSTS File + (+ exchange.local.domain exchange host)
    Test-Sync status: Normal

    EAC configurations
    Server / Mailbox / DNS Lookup:
    - WAN: external network adapter DNS 8.8.8.8 +
    - Local: + DNS internal network adapter "AD IP"
    - Type Certificate UCC installed (if it can change something?)

    Mail Flow:
    - Sent EdgeSync Connector Default: MX + server use external DNS

    On the local DNS server (AD), with or without forward to 8.8.8.8 does not change anything.


    What did I forget?
    Thanks for your help

    Saturday, December 19, 2015 11:32 PM

Answers

  • Thank you Praveen, but I've already done this (problem for all remote domain), no change.

    - Configure external DNS in EAC / Servers 

    - Configure use external dns in EAC / Send flow Default EdgeSync 

    And I don't know if there is an Edge or Hub problem ?

    Any help ?

    --------------------------------------------------

    Oh my ...

    Configured HOST file like that : 

    exchange.local IP 
    Instead of
    IP exchange.local

    Big problem for (very) small detail :(

    Resolved ! 

    • Edited by Jayce68 Sunday, December 20, 2015 9:39 AM
    • Marked as answer by Jayce68 Sunday, December 20, 2015 9:39 AM
    Sunday, December 20, 2015 8:37 AM

All replies

  • Hi,

    Please follow the below article

    https://support.microsoft.com/en-us/kb/3038746

    Regards,

    Praveen

    ----------------------------------------------------------------------

    Remember to mark as helpful if you find my contribution useful or as an answer if it does answer your question.That will encourage me - and others - to take time out to help you Check out my latest blog posts on Exchange 2016 @ Techrid.com

    Sunday, December 20, 2015 4:08 AM
  • Thank you Praveen, but I've already done this (problem for all remote domain), no change.

    - Configure external DNS in EAC / Servers 

    - Configure use external dns in EAC / Send flow Default EdgeSync 

    And I don't know if there is an Edge or Hub problem ?

    Any help ?

    --------------------------------------------------

    Oh my ...

    Configured HOST file like that : 

    exchange.local IP 
    Instead of
    IP exchange.local

    Big problem for (very) small detail :(

    Resolved ! 

    • Edited by Jayce68 Sunday, December 20, 2015 9:39 AM
    • Marked as answer by Jayce68 Sunday, December 20, 2015 9:39 AM
    Sunday, December 20, 2015 8:37 AM
  • Run the below command to know your environment

    Get-ExchangeServer | fl name,domain,edition,fqdn,serverrole,site,admindisplayversion

    Please follow the below article and update

    http://msexchangeguru.com/2013/11/23/451-4-4-0-dns-query-failed-the-error-was-smtpsend-dns-nonexistentdomain-nonexistent-domain/

    Regards,

    Praveen

    ----------------------------------------------------------------------

    Remember to mark as helpful if you find my contribution useful or as an answer if it does answer your question.That will encourage me - and others - to take time out to help you Check out my latest blog posts on Exchange 2016 @ Techrid.com

    Sunday, December 20, 2015 9:39 AM