Configure external DNS for Exchange

After installing Exchange Server, the next step is to configure external DNS for Exchange. It’s important to keep the same namespace internal and external. We will sign in to the public DNS and create the records for Exchange Server. In this article, you will learn how to configure external DNS for Exchange Server.

Information Public DNS Exchange

Important: Read the article Exchange namespace design and planning before going further.

There are three records types that we will add to the public DNS. About the values, you should only enter an IP address for the A record. The MX record is the spam filter, and the CNAME (alias) should point to the DNS name of the A record for the Exchange server. If your IP address changed due to changing Internet Service Providers, you would only need to update the A record.

Note: Always use a spam filter to protect your Exchange Server organization from incoming and outgoing spam. The one we recommend is the SpamBull cloud spam filter.

Record Type	TTL	DNS Name	Priority	Value
A	300	mail.exoip.com		73.122.35.127
CNAME	300	autodiscover.exoip.com		mail.exoip.com.
MX	300	@	10	mx1.spambull.com.
MX	300	@	20	mx2.spambull.com.
MX	300	@	30	mx3.spambull.com.
MX	300	@	40	mx4.spambull.com.

An architecture view of the Exchange namespace is shown below in the diagram.

Create Public DNS records

Sign in to your external DNS registrar. Configure the records.

Check the Public DNS records

Let’s run the Resolve-DnsName cmdlet to verify the:

• MX record
• A record
• Autodiscover record

Run PowerShell as administrator. Run the Resolve-DnsName cmdlet and the -Server parameter. The -Server parameter will resolve the name against the Google DNS servers. We can check the Public DNS records on the LAN or any external network.

Note: Don’t immediately resolve the external DNS records, as that will not work. The servers around the world have not reflected the changes. Give it a maximum of an hour as the DNS propagation will need time.

Check MX record

Verify the MX record.

PS C:\> Resolve-DnsName -Type MX exoip.com -Server 8.8.8.8 | Format-Table -AutoSize

Name      Type TTL Section NameExchange     Preference
----      ---- --- ------- ------------     ----------
exoip.com MX   300 Answer  mx1.spambull.com 10
exoip.com MX   300 Answer  mx2.spambull.com 20
exoip.com MX   300 Answer  mx3.spambull.com 30
exoip.com MX   300 Answer  mx4.spambull.com 40

Check A record

Let’s have a look at the public A record.

PS C:\> Resolve-DnsName -Type A mail.exoip.com -Server 8.8.8.8 | Format-Table -AutoSize
                                              
Name           Type TTL Section IPAddress
----           ---- --- ------- ---------
mail.exoip.com A    300 Answer  73.122.35.127

Check autodiscover record

As of last, let’s check the public autodiscover record.

PS C:\> Resolve-DnsName -Type TXT autodiscover.exoip.com -Server 8.8.8.8 | Format-Table -AutoSize

Name                   Type  TTL Section NameHost
----                   ----  --- ------- --------
autodiscover.exoip.com CNAME 300 Answer  mail.exoip.com

Conclusion

You learned how to configure External DNS for Exchange Server. Add the three records to your public DNS and verify that you can resolve the external DNS records. Don’t forget that it can take a little time before you can resolve the DNS.

Did you enjoy this article? You may also like Configure internal DNS for Exchange. Don’t forget to follow us and share this article.