How can you create a calculated field in Splunk?

Creating a calculated field in Splunk allows you to generate new fields based on evaluations or calculations performed on existing data. The correct option, defining a new field based on an expression in settings, is appropriate because it reflects the method of using Splunk's interface to create a calculated field.

When you define a calculated field in the settings, you specify an expression that defines how the field is calculated based on your data. This approach leverages the Splunk configuration to create fields that will be available in your searches and reports consistently, allowing for more sophisticated analysis without altering the original data.

The method of using the eval command in a search is beneficial for performing on-the-fly calculations during a search but does not create a persistent calculated field that can be reused across different searches and dashboards. Creating values within the app configuration file is more about managing app settings rather than defining fields. Importing from an external source is outside the context of calculated fields, as it involves bringing data into Splunk, rather than generating new fields from existing data.