The correct answer is D. | eval notNULL = "" fillnull value=0 notNULL
Option A is incorrect because it is missing a comma between the "0" and the notNULL in the if function. The correct syntax for the if function is if (condition, true_value, false_value).
Option B is incorrect because it is missing the false_value argument in the if function. The correct syntax for the if function is if (condition, true_value, false_value).
Option C is incorrect because it uses the nullfill command, which only replaces null values, not empty strings.
The nullfill command is equivalent to fillnull value=null.
Option D is correct because it uses the eval command to assign an empty string to the notNULL field, and then uses the fillnull command to replace the empty string with a zero. The fillnull command can replace any value with a specified replacement, not just null values.

The correct syntax to find events associated with a tag in Splunk is tag=<value>1. So, the correct answer is D.
tag=<value>. This syntax allows you to annotate specified fields in your search results with tags1.
In Splunk, tags are a type of knowledge object that you can use to add meaningful aliases to field values in your data1. For example, if you have a field called status_code in your data, you might have different status codes like 200, 404, 500, etc. You can create tags for these status codes like success for 200, not_found for
404, and server_error for 500. Then, you can use the tag command in your searches to find events associated with these tags1.
Here is an example of how you can use the tag command in a search:
index=main sourcetype=access_combined | tag status_code
In this search, the tag command annotates the status_code field in the search results with the corresponding tags. If you have tagged the status code 200 with success, the status code 404 with not_found, and the status code 500 with server_error, the search results will include these tags1.
You can also use the tag command with a specific tag value to find events associated with that tag. For example, the following search finds all events where the status code is tagged with success:
index=main sourcetype=access_combined | tag status_code | search tag::status_code=success In this search, the tag command annotates the status_code field with the corresponding tags, and the search command filters the results to include only events where the status_code field is tagged with success1.

In Splunk, a macro can accept arguments, and the correct syntax for a macro that takes two arguments is macro_name(argument1, argument2). In this case, the macro is called samplemacro, and it accepts two arguments, so the correct format would be samplemacro(1,2). This syntax allows for passing dynamic values into the macro, which can then be used to modify the search dynamically based on the arguments provided.
References:
* Splunk Docs - Macros

GET workflow actions are custom actions that open a URL link when you click on a field value in your search results. GET workflow actions can be configured with various options, such as label name, base URL, URI parameters, app context, etc. One of the options is to choose whether to open the URL link in the current window or in a new window. GET workflow actions do not have to be configured with POST arguments, as they use GET method to send requests to web servers. Configuration of GET workflow actions does not include choosing a sourcetype, as they do not generate any data in Splunk. Label names for GET workflow actions must include a field name surrounded by dollar signs, as this indicates the field value that will be used to replace the variable in the URL link.

The datamodel command is a generating command that searches a data model.
Extract: "The datamodel command lets you search data model datasets. It returns events from the data model when used with the search keyword." Thus, the search returns events from the data model Application_State.