This is because an event type is a knowledge object that assigns a user-defined name to a set of events that match a specific search criteria. For example, you can create an event type named successful_purchase for events that have sourcetype=access_combined, status=200, and action=purchase. Then, you can use eventtype=successful_purchase as a search term to find those events. You can also use event types to create alerts, reports, and dashboards.You can learn more about event types from the Splunk documentation1. The other options are incorrect because they do not describe what an event type is. A log level measurement is a field that indicates the severity of an event, such as info, warn, or error. A knowledge object that is applied before fields are extracted is a source type, which identifies the format and structure of the data. Either a log, a metric, or a trace is a type of data that Splunk can ingest and analyze, but not an event type.

The correct answer is D. eval.

A calculated field is a field that is added to events at search time by using an eval expression. A calculated field can use the values of two or more fields that are already present in the events to perform calculations. A calculated field can be defined with Splunk Web or in the props.conf file. They can be used in searches, reports, dashboards, and data models like any other extracted field1.

A calculated field is a shortcut for performing repetitive, long, or complex transformations using the eval command. The eval command is used to create or modify fields by using expressions. The eval command can perform mathematical, string, date and time, comparison, logical, and other operations on fields or values2.

For example, if you want to create a new field named total that is the sum of two fields named price and tax, you can use the eval command as follows:

| eval total=price+tax

However, if you want to use this new field in multiple searches, reports, or dashboards, you can create a calculated field instead of writing the eval command every time. To create a calculated field with Splunk Web, you need to go to Settings > Fields > Calculated Fields and enter the name of the new field (total), the name of the sourcetype (sales), and the eval expression (price+tax). This will create a calculated field named total that will be added to all events with the sourcetype sales at search time. You can then use the total field like any other extracted field without writing the eval expression1.

The other options are not correct because they are not related to calculated fields. These options are:

A) transaction: This command is used to group events that share some common values into a single record, called a transaction. A transaction can span multiple events and multiple sources, and can be useful for correlating events that are related but not contiguous3.

B) lookup: This command is used to enrich events with additional fields from an external source, such as a CSV file or a database. A lookup can add fields to events based on the values of existing fields, such as host, source, sourcetype, or any other extracted field.

C) stats: This command is used to calculate summary statistics on the fields in the search results, such as count, sum, average, etc. It can be used to group and aggregate data by one or more fields.

About calculated fields

eval command overview

transaction command overview

[lookup command overview]

[stats command overview]

The commandsourcetype=access_combined | transaction JSESSIONIDdoes three things:

It filters the events by the sourcetypeaccess_combined, which is a predefined sourcetype for Apache web server logs.

It groups the events by the fieldJSESSIONID, which is a unique identifier for each user session.

It creates a single event from each group of events that share the sameJSESSIONIDvalue. This single event will have some additional fields created by the transaction command, such asduration,eventcount, andstartime.

Therefore, the statements B, C, and D are true.

Theevalcommand is a Splunk command that allows you to create or modify fields using expressions .

Theiffunction is an expression that evaluates a condition and returns a value based on whether the condition is true or false. The syntax of theiffunction isif(X,Y,Z), where X is the condition, Y is the value to return if X is true, and Z is the value to return if X is false.

Theisnotnullfunction is an expression that returns true if the argument is not null, and false otherwise. The syntax of theisnotnullfunction isisnotnull(X), where X is the argument to check.

Therefore, the expressionif (isnotnull (src), src, host)returns the value ofsrcif it is not null, and the value ofhostotherwise. This means that it will provide a new value forhostfromsrcif it exists, and keep the original value ofhostotherwise.