C100DEV Indexing Practice Question
You are considering using a hashed index for a 'product_id' field to distribute data across shards. Which of the following is a known limitation of hashed indexes in MongoDB?
⚠ Common exam trap
Many test-takers confuse hashed indexes with standard indexes, mistakenly believing they support range queries or sorting because they distribute data evenly across shards for equality lookups.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Hashed indexes do not support range-based queries or sort operations.
Hashed indexes compute a hash of the value of a field and use that hash to create the index. While this is great for equality matches and even distribution in sharding, it destroys the natural ordering of the data. Consequently, hashed indexes cannot support range-based queries (like greater than or less than) or sorting operations.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Hashed indexes do not support equality matches, only range queries.
Why it's wrong here
Hashed indexes are specifically designed for equality matches. They take a value, compute its hash, and look it up in the index. They are the opposite of range-query friendly; they excel at finding a specific document but are incapable of identifying a set of documents within a specific numerical or alphabetical range.
- ✗
Hashed indexes can only be created on fields that contain unique values.
Why it's wrong here
Hashed indexes do not require the underlying values to be unique. Multiple documents can have the same value for a field, and they will simply hash to the same value and be indexed accordingly. However, they do not support the 'unique' constraint themselves, meaning you can't enforce uniqueness via a hashed index.
- ✓
Hashed indexes do not support range-based queries or sort operations.
Why this is correct
Because hashing transforms values into a pseudo-random distribution, the original order of the data is lost. A query for values greater than 100 cannot use a hashed index because the hash of 101 might be numerically smaller or larger than the hash of 1000, making the B-tree structure useless for ranges.
- ✗
Hashed indexes are only available in the MongoDB Enterprise Edition.
Why it's wrong here
Hashed indexes are a core feature of the MongoDB Community Edition and are widely used in sharded clusters for both community and enterprise users. They are essential for achieving uniform data distribution across shards when the shard key does not have naturally high cardinality or has a monotonically increasing value.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official MongoDB exam blueprint
This C100DEV practice question is part of Courseiva's free MongoDB certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the C100DEV exam.