When you troubleshoot Simple Mail Transfer Protocol (SMTP) problems, you may want to obtain the Domain Name System (DNS) records for the SMTP domain in question. You can use the Nslookup.exe utility to collect this information.

DNS must be configured properly on the computer running the Nslookup.exe utility. If DNS is not configured, an error message is displayed when the Nslookup.exe utility starts.


Steps to Use the Nslookup.exe Utility

1. Open a command prompt.

2. Type the following:

nslookup

3. Type the following:

set q=mx
This sets a filter to only collect Internet Mail Exchanger (MX) records and related information.

4. Type the following

domain_name.com
where domain_name is the domain that you want to obtain the DNS records for, for example, microsoft.com  
An output similar to the following is displayed:
Server: [157.178.72.30]
Address: 157.178.72.30

microsoft.com MX preference = 10, mail exchanger = mail1.microsoft.com
microsoft.com MX preference = 10, mail exchanger = mail2.microsoft.com
microsoft.com MX preference = 10, mail exchanger = mail3.microsoft.com
microsoft.com MX preference = 10, mail exchanger = mail4.microsoft.com
microsoft.com MX preference = 10, mail exchanger = mail5.microsoft.com
mail1.microsoft.com internet address = 131.107.3.125
mail2.microsoft.com internet address = 131.107.3.124
mail3.microsoft.com internet address = 131.107.3.123
mail4.microsoft.com internet address = 131.107.3.122
mail5.microsoft.com internet address = 131.107.3.121