In what scenario would you typically use an External ID in Salesforce?

Using an External ID in Salesforce is primarily advantageous for ensuring unique identification of records. External IDs are custom fields that you define on an object to store an identifier from an external system, which helps to maintain data consistency and integrity when integrating Salesforce with that external system.

When importing data into Salesforce or syncing data between systems, External IDs allow for the matching of records against those in the external system. This ensures that updates can be performed accurately without creating duplicates or conflicting entries, as the External ID serves as a unique reference point.

For scenarios where one needs to update or insert records from outside systems, leveraging an External ID simplifies this process significantly. It provides a reliable method to identify records uniquely, which is crucial in maintaining data quality across platforms.

The other scenarios listed do not directly relate to the primary function of External IDs: validation may involve different mechanisms, connecting Salesforce with external databases encompasses a wider array of integration methods, and historical data retention focuses more on data archiving rather than record identification.