What happens to field2 when an event contains only field1 with alias overwrite selected?

SPLK-1002 By islever Editorial Last updated

Short answer

D field2 values are replaced with the value of the field1.

Question

A field alias is created where field1 = field2 and the Overwrite Field Values checkbox is selected. What happens if an event only contains values for field1?
  1. field1 and field2 values are merged.
  2. field2 values are removed from the events.
  3. field2 values are unchanged.
  4. field2 values are replaced with the value of the field1. Correct Answer

Key Takeaways

The question tests whether you understand that Overwrite Field Values forces the alias destination field to adopt the source field's value even when the destination is absent or empty.

Learn what Splunk's 'Overwrite Field Values' checkbox does for field aliases when only one field has a value. The community confirms that field2 is replaced by field1's value, with 75% of voters selecting option D.

Common mistake: Option C is the common mistake: test takers assume that if field2 has no value in the event, it stays unchanged; in reality, the overwrite option actively replaces it with field1's value.

Expert Analysis

Why the Answer Is Correct

Option D is correct because when you create a field alias with "Overwrite Field Values" checked, Splunk will force the alias destination field to use the source field's value whenever it exists. If the event only contains a value for field1, field2 is created or replaced with field1's value. This is explicitly described in Splunk's documentation and supported by the majority of test takers (75% voted D).

Why the Other Options Are Wrong

Option A "field1 and field2 values are merged" is incorrect because an alias does not merge values; it points one field to another. Option B "field2 values are removed" is wrong because the value is copied, not deleted. Option C "field2 values are unchanged" is the most common distracter; it would be true only if Overwrite Field Values were unchecked, but with the checkbox selected, Splunk replaces field2 with field1's value, even if field2 was originally empty.

Community Comment Notes

User comment [1] explains the exact behavior: "Select Overwrite field values if you want your field alias to remove the field alias name when the original field does not exist or has no value, or replace the field alias name with the original field name when the field alias name already exists." This aligns with answer D. Comment [2] incorrectly argues for C, but comment [3] counters: "I tested, D correct ans," which matches practical verification. Trust the tested behavior over theoretical reasoning.

Official Reference

https://kinneygroup.com/blog/splunk-fields-of-dreams-how-to-create-calculated-fields-and-aliases/

This link opens the official vendor documentation in a new tab.

Exam Strategy

Remember the Overwrite Field Values option is a checkbox that changes the behavior of aliases. When it's unchecked, field2 keeps its own value if it exists; when checked, field1's value always takes precedence. On exam day, watch for whether the question mentions this checkbox, and don't assume that missing fields remain untouched.

Community Votes

D
75%
C
25%

75% of anonymous learners picked answer D. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

  1. FrozenYeti 👍 2 Answered D
    Select Overwrite field values if you want your field alias to remove the field alias name when the original field does not exist or has no value, or replace the field alias name with the original field name when the field alias name already exists. REF: https://kinneygroup.com/blog/splunk-fields-of-dreams-how-to-create-calculated-fields-and-aliases/#:~:text=(Optional)%20Select%20Overwrite%20field%20values,Click%20Save.
  2. ismailwale 👍 1 Answered C
    Option C is more correct: Explanation: In Splunk, if an event has values for only one field (like field1) and not for another field (like field2), then the values of field2 remain unchanged in the context of that particular event. Field2 will still retain whatever values it has from previous events or selections if it is present. Here’s a breakdown of the other options for clarification: A. field1 and field2 values are merged.: This is incorrect. There is no merging of values; each field retains its own values independently. B. field2 values are removed from the events.: This is incorrect. Values for field2 are not removed; they simply are not present in this specific event. D. field2 values are replaced with the value of field1.: This is incorrect. Values in field2 are not replaced by any value from field1 unless specifically programmed to do so with a command.
  3. alexoancea08 👍 1 Answered D
    I tested, D correct ans

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