Question 1mediummultiple choice
Full question →mediummultiple choiceObjective-mapped
You are developing an IoT solution that stores device metadata (device ID, location, firmware version, last seen timestamp) in Azure Table Storage. Each device has a unique DeviceId and a Timestamp. You need to design the PartitionKey and RowKey to optimize query performance for the following query: Retrieve all firmware versions for devices in a specific city that were last seen within the last 24 hours. The query must be efficient (partition scan minimized). Which key design is most appropriate?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Distractor review
PartitionKey = City, RowKey = DeviceId_Timestamp (e.g., "device123_2023-10-01T12:00:00")
This design allows querying by city but the row key is not sortable by timestamp, so you cannot do a range query on timestamp efficiently. You would have to scan all devices in the city and filter in the client.
B
Best answer
PartitionKey = City, RowKey = Inverted timestamp (e.g., DateTime.MaxValue.Ticks - Timestamp.Ticks)
This design keeps all devices from the same city in one partition (efficient for city filtering). The row key, when sorted in ascending order, brings the most recent timestamps first. You can use a range query on the row key to get devices with last seen within the last 24 hours by comparing against the inverted timestamp of 24 hours ago.
C
Distractor review
PartitionKey = DeviceId, RowKey = Timestamp
Partitioning by DeviceId scatters data across partitions, meaning a query for devices in a specific city would require a full table scan (all partitions) to find matching cities, which is inefficient.
D
Distractor review
PartitionKey = City, RowKey = DeviceId
This allows efficient partition query by city, but the row key is device ID. To filter by timestamp, you would need to scan all rows in the partition and apply a filter, which is not efficient if the partition has many devices.
Common exam trap
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Technical deep dive
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
Related practice questions
Related AZ-204 practice-question pages
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
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Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
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FAQ
Questions learners often ask
What does this AZ-204 question test?
Static NAT maps one inside address to one outside address.
What is the correct answer to this question?
The correct answer is: PartitionKey = City, RowKey = Inverted timestamp (e.g., DateTime.MaxValue.Ticks - Timestamp.Ticks) — To efficiently query devices by city and timestamp, you should partition by city (so all devices in a city are in the same partition) and use the timestamp as row key (so you can range query on timestamp). Option A uses PartitionKey = City and RowKey = combined device ID and timestamp, but that makes row key not sortable by timestamp alone. Option B uses PartitionKey = City and RowKey = Timestamp (inverted, e.g., DateTime.MaxValue.Ticks - ticks) so that recent timestamps come first. However, a range query on timestamp can still be done if the row key is sorted. Option C partitions by device ID, which is not helpful for city queries. Option D uses PartitionKey = City and RowKey = DeviceId, which does not allow efficient timestamp filtering because the row key is not timestamp. The best design is to use PartitionKey = City and RowKey = inverted timestamp to allow range queries on time. In Azure Table Storage, you can query with a filter on RowKey using 'ge' and 'le'. Option B correctly describes this pattern.
What should I do if I get this AZ-204 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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