How to Verify that Exchange Servers Can Resolve Internal DNS Names

Article
08/08/2014

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 Begin

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.

Procedure

How to verify that Exchange Servers can resolve internal DNS names

On your Exchange Server, open a command prompt, navigate to the following directory and type the following:
```
<drive letter>:\WINDOWS\system32\inetsrv
```
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.

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

        QNAME = example.microsoft.com
        Type = MX (0xf)
        Flags =  UDP default, TCP on truncation (0x0)
        Protocol = UDP
        DNS Servers: (DNS cache will not be used)
        172.16.1.101
Connected to DNS 172.16.1.101 over UDP/IP.
Received DNS Response:
----------------------
        Error: 9501
        Description: No records could be located for this name
        These records were received:
        microsoft.com   SOA      

Querying via DNSAPI:
--------------------
        QNAME = example.microsoft.com
        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:
        example.microsoft.com    A    172.16.1.106
1 A record(s) found for example.microsoft.com
Target hostnames and IP addresses
---------------------------------
HostName: "example.microsoft.com"
        172.16.1.106.