dig command is a very useful DNS lookup utility. It can be used to retrieve DNS records information of any domain name by querying specifc DNS servers. It is also a great troubleshooting tool for any admin configuring or troubleshooting existing DNS server.
This is a companion discussion topic for the original entry at https://linuxconfig.org/how-to-check-domain-s-mx-mail-exchange-records-using-dig-command-on-linux