# Distributed Cache (Focus: Hashing & System Logic)

- Question: Implement a Cache Router

  Level 1 (Easy - Modulo Hashing): Write a function that maps a key (string) to one of N servers.

      Task: Implement getServerIndex(key, serverCount).

      Expected Logic: Simple hash modulo: hash(key) % serverCount.

      Critique: The interviewer will ask, "What happens to the existing keys if we add one server (change N to N+1)?" (Answer: Almost all keys get remapped, causing a massive cache miss storm).

  Level 2 (Medium - Consistent Hashing): Solve the remapping problem. Implement a ConsistentHash class.

      Task: Map servers to points on a circle (0 to 360 degrees or a large integer range). Map keys to the same circle. A key belongs to the first server it encounters moving clockwise.

      Goal: Prove that adding a server only requires remapping the keys that fall between the new server and its predecessor.

  Level 3 (Hard - Virtual Nodes): The servers have uneven capacity, or the data distribution is skewed (some segments of the ring have way more keys).

      Task: Modify the class so that each physical server exists at multiple points on the ring (e.g., "Server A" is at positions 10, 150, and 290).

      Goal: Distribute load more evenly and handle "hot spots" better.

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Questions:

  - Async
  - Threads
  - DB 
  - Cache
  - KV
  - Distribution


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FE

 - Fetching URL
    - Storing it as useMemo and what not.