I don’t know how many times a day/week I do this to troubleshoot various issues with email systems. Good command in general to remember and use.
It’s really easy to use nslookup to lookup MX records for a domain.
nslookup -type=mx google.com
C:>nslookup -type=mx google.com Server: ns1.domain.local Address: 10.147.204.18 Non-authoritative answer: google.com MX preference = 10, mail exchanger = aspmx.l.google.com google.com MX preference = 30, mail exchanger = alt2.aspmx.l.google.com google.com MX preference = 40, mail exchanger = alt3.aspmx.l.google.com google.com MX preference = 50, mail exchanger = alt4.aspmx.l.google.com google.com MX preference = 20, mail exchanger = alt1.aspmx.l.google.com
You can see that the server used to query is ns1.domain.local. The key here is “-type=mx”. There are many other options you can use in place of “mx”. Take a look at nslookup /? for additional options!
You can expand this further and resolve the returned MX records to IP address:
nslookup aspmx.l.google.com
C:>nslookup aspmx.l.google.com
Server: ns1.domain.local
Address: 10.147.204.18
Non-authoritative answer:
Name: aspmx.l.google.com
Addresses: 2607:f8b0:4001:c02::1b
74.125.133.26
You can see that this has both an ipv4 and ipv6 resolved address.
