Splunk Core Certified User Practice Exam

The use of the OUTPUTNEW clause in a lookup command is specifically designed to prevent existing fields from being overwritten. When you apply this clause, it ensures that if a field with the same name already exists in the event, the lookup value will not replace it. Instead, only new fields that do not already exist will be added to the event.

This is particularly useful when you want to enrich events with additional information from the lookup without losing any existing data. For example, if you have a lookup that contains user information and you already have fields like "username" in your events, using OUTPUTNEW will allow you to bring in new fields from the lookup, like "user_email", without replacing the existing "username" field in your events.

The other options do not serve this intended purpose effectively. KEEPFIELDS, for instance, allows you to retain specified fields but does not prevent overwriting; rather, it is primarily concerned with which fields to keep in the result set. OVERWRITE explicitly allows overwriting existing fields, while NEWOUTPUT is not a recognized clause in the context of lookups. Thus, OUTPUTNEW is the correct choice for preventing overwriting.