Explain Types of Cache & Their Characteristics

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Ravi Vishwakarma · Answer

Types of Cache & Their Characteristics Cache Type Where Used Key Characteristics 1. CPU Cache Inside the processor (L1, L2, L3) - Extremely fast- Very small size- Stores frequently accessed instructions/data 2. Memory Cache RAM-based caching in applications - Faster than disk- Stores app data (e.g., user sessions)- Volatile 3. Disk Cache Operating systems, databases - Slower than RAM- Larger size- Persists across restarts 4. Web Browser Cache Local browser storage - Stores CSS, JS, images- Reduces page load time- Can expire or be cleared 5. CDN Cache Content Delivery Networks (edge servers) - Geographically distributed- Reduces latency- Caches static resources 6. Database Cache App layer or built-in (e.g., Redis, Memcached) - Reduces DB load- Stores query results or objects- Configurable expiration 7. Application/Server Cache Web apps, APIs (e.g., ASP.NET, Node.js) - Speeds up data access- Often in-memory- Can be per-user or global 8. File System Cache OS-level or app-level file reads - Caches file contents- Speeds up repeated file access 9. DNS Cache Browsers and OS networking layers - Stores resolved IPs- Reduces DNS lookup time General Characteristics of Caching Characteristic Description Speed Access time is much faster than the original source (DB, disk, etc.) Volatile Many caches (RAM-based) are temporary and cleared on restart Size-Limited Cache storage is limited, managed by eviction policies (e.g., LRU, FIFO) Staleness Cached data can become outdated; needs invalidation or expiration logic Eviction Policy Strategy to remove old or least-used items (e.g., LRU = Least Recently Used) Write Policy Write-through / write-back determines how updates sync with the original source Transparency Often invisible to users; operates behind the scenes Real-World Analogy Think of cache as a frequently used tool placed on your desk — instead of going to a toolbox every time, you keep it within reach for speed.

Characteristic	Description
Speed	Access time is much faster than the original source (DB, disk, etc.)
Volatile	Many caches (RAM-based) are temporary and cleared on restart
Size-Limited	Cache storage is limited, managed by eviction policies (e.g., LRU, FIFO)
Staleness	Cached data can become outdated; needs invalidation or expiration logic
Eviction Policy	Strategy to remove old or least-used items (e.g., LRU = Least Recently Used)
Write Policy	Write-through / write-back determines how updates sync with the original source
Transparency	Often invisible to users; operates behind the scenes

Cache Type	Where Used	Key Characteristics
1. CPU Cache	Inside the processor (L1, L2, L3)	- Extremely fast- Very small size- Stores frequently accessed instructions/data
2. Memory Cache	RAM-based caching in applications	- Faster than disk- Stores app data (e.g., user sessions)- Volatile
3. Disk Cache	Operating systems, databases	- Slower than RAM- Larger size- Persists across restarts
4. Web Browser Cache	Local browser storage	- Stores CSS, JS, images- Reduces page load time- Can expire or be cleared
5. CDN Cache	Content Delivery Networks (edge servers)	- Geographically distributed- Reduces latency- Caches static resources
6. Database Cache	App layer or built-in (e.g., Redis, Memcached)	- Reduces DB load- Stores query results or objects- Configurable expiration
7. Application/Server Cache	Web apps, APIs (e.g., ASP.NET, Node.js)	- Speeds up data access- Often in-memory- Can be per-user or global
8. File System Cache	OS-level or app-level file reads	- Caches file contents- Speeds up repeated file access
9. DNS Cache	Browsers and OS networking layers	- Stores resolved IPs- Reduces DNS lookup time

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Explain Types of Cache & Their Characteristics

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Types of Cache & Their Characteristics

General Characteristics of Caching

Real-World Analogy