DNS zone propagation is the process of updating a domain's information on the internet. When changes like nameserver adjustments or adding MX records for email occur, propagation begins. These changes are automatically communicated to DNS servers worldwide, taking up to 24 hours for full update due to the global reach. The time can vary based on the record type, with NS and A records often updating faster. In some cases, specific records might take up to 72 hours to propagate fully.