What must be done before an automatic lookup can be created?

To create an automatic lookup in Splunk, it is essential first to establish a lookup definition. This definition serves as the bridge between the lookup file and the data that will utilize it. By creating a lookup definition, you specify how the system should interact with the designated lookup file when processing search commands. This step establishes the parameters of the lookup, allowing Splunk to know which fields in your event data correlate with the fields in your lookup file.

While having the lookup file uploaded and accessible is also a prerequisite for the automatic lookup to function effectively, the creation of the lookup definition sets the framework that allows Splunk to automatically apply the lookup as specified during data processing. This is why defining the lookup is a critical initial step.