How to Verify that Exchange Servers Can Resolve Internal DNS Names


Topic Last Modified: 2005-11-14

When SMTP queries DNS, it always queries for MX records first. If an internal MX record exists and/or it is incorrectly configured, your internal mail delivery may not work.

Before you perform the procedure in this topic, read Verifying DNS Design and Configuration.

The SMTP DNS Diagnostic Tool is available for use on Exchange Servers running Microsoft® Windows® Server™ 2003. The SMTP DNS Diagnostic Tool simulates the internal code path of the SMTP service and generates diagnostic messages that indicate how DNS resolution is proceeding.

Run the SMTP DNS Diagnostic Tool on the computer for which you want to verify DNS configuration. Your path should include %WINDIR%\System32\Inetsrv so that the tool works.

The SMTP DNS Diagnostic Tool is included with the Windows Server 2003 Resource Kit Tools and you can downloaded it from the Windows Server 2003 Resource Kit Tools Web page.

  1. On your Exchange Server, open a command prompt, navigate to the following directory and type the following:

    <drive letter>:\WINDOWS\system32\inetsrv
  2. Type the following:

    dnsdiag internal host name -v 1

    Where internal host name is the fully qualified domain name of another Exchange Server in your organization.

  3. Verify that the correct IP address of the Exchange Server is returned. Your output should look similar to the following:

            QNAME =
            Type = MX (0xf)
            Flags =  UDP default, TCP on truncation (0x0)
            Protocol = UDP
            DNS Servers: (DNS cache will not be used)
    Connected to DNS over UDP/IP.
    Received DNS Response:
            Error: 9501
            Description: No records could be located for this name
            These records were received:
    Querying via DNSAPI:
            QNAME =
            Type = A (0x1)
            Flags =  DNS_QUERY_TREAT_AS_FQDN, (0x1000)
            Protocol = Default UDP, TCP on truncation
            Servers: (DNS cache will be used)
            Default DNS servers on box.
    Received DNS Response:
            Error: 0
            Description: Success
            These records were received:
    1 A record(s) found for
    Target hostnames and IP addresses
    HostName: ""

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