MartyDig is a bash script I made early in my linux web hosting support days, to quickly determine DNS issues for a given domain. Over time it has evolved to be mainly email focused, specifically on SPF/DKIM/DMARC issues and nameserver troublshooting.

1) paste script into /usr/local/bin/
3) chmod +x /usr/local/bin/
3) run by typing ‘mdig’

Here is an example output