MX Records stands for Mail Exchange Records and is a DNS record that is responsible for email routing. MX Records have two values. The first tells a destination and the second a priority for that destination. This allows for redundancy and makes the system reliable.
Below is an example of GMail’s MX Records:
Priority is given to the lowest number first and then cascades to the next if it fails. Typically when you input these records, there will be separate fields for each value.