What happens if a user attempts to create an index with a leading underscore?

When a user attempts to create an index with a leading underscore, the operation is not permitted, and the index creation will fail. In Splunk, indexes that start with an underscore are reserved for system use and cannot be created by users. This is a protective measure to ensure that system indexes, such as those used for internal operations, are not inadvertently overwritten or misconfigured by user actions. The naming convention enforces clarity and prevents potential conflicts or confusion between user-created indexes and those reserved by Splunk for critical functionality. Such constraints help maintain the integrity and optimal performance of the Splunk environment.