Another handy tool for making DNS queries is DIG.
(This is the default and simplest query, but it will provide you with a treasure trove of DNS info)
dig +nocmd domain.domain MX +noall +answer
(The nocmd option specifies that the request details should not be in the output, and the trailing part will ensure that the query only returns the answer)
You can also attempt a DNS zone transfer – which will transfer the entire DNS zone file; if the target server is incorrectly configured:
dig domain.domain AXFR +noall +answer
If successful you will have all DNS entries displayed on screen.
To attempt the DNS transfer from a specific DNS server you can use:
dig domain.domain AXFR +noall +answer @dns.domain.domain