Exam CRT-450 topic 1 question 290 discussion

B. Build a flow with Flow Builder: Create a Flow using Flow Builder to perform the logic of looking up the Timezone value based on the Postal Code from the "PostalCodeToTimezone__c" custom object. Flows offer flexibility and can interact with custom objects and perform complex logic. Then, use Process Builder to trigger the Flow when an Account is edited, and the Postal Code field changes. In the Flow, you can perform the necessary query to fetch the Timezone based on the Postal Code and update the "Timezone" custom field on the Account accordingly.

this appears on the exam, it is B, why else would you write a trigger

The formula field is technically possible but is not a very practical implementation. The formula field is only able to reference a related record to the one it is in. We don't have details about exactly how PostalCodeToTimezone__c works, but supposing there's a single record for every PC with its timezone, this would require to associate the corresponding record to each Account, defeating the purpose of the automation. A Flow would be way more practical; just a simple record lookup using the current PC value to retrieve the corresponding timezone and set it to the Account, that adding that it can be made into a "Fast Field Updates" flow makes it the best option.

Formula field is not on real exam. I believe it should be either a record triggered flow or a trigger

Formula field is not on real exam. I believe it should be either a record triggered flow or a trigger