| Model | Layers / Tiers | Most Famous For | Best For Beginners? | Still Used Daily in 2025? |
|---|---|---|---|---|
| TCP/IP Model (Internet Model) |
4 layers Network Access → Internet → Transport → Application |
How the actual Internet works (YouTube, Wi-Fi, everything) | YES – Start here! | Every single day |
| Cisco 3-Layer Hierarchical (Access – Distribution – Core) |
3 layers | User → Switches → Routers → Servers | Yes – super common | Every company network |
| Three-Tier Application Model (User → App → Oracle/DB) |
3 tiers Client → Application Server → Database |
Oracle, Java, APEX, almost every web app | Yes – if you do web/apps | Every enterprise app |
| OSI Model | 7 layers Physical → Data Link → Network → Transport → Session → Presentation → Application |
Exams & interviews | Learn 3rd or 4th | Only for certifications |
| Two-Tier (Client–Server) | 2 tiers | Old desktop apps, some internal tools | Sometimes | Still around |
| N-Tier / Microservices (Modern Cloud) | 4–10+ tiers | AWS, Netflix, microservices | When you go cloud | Dominant in 2025 |
| Collapsed Core (2-Layer) | 2 layers | Small & medium companies | Very common | Everywhere |
| Spine-Leaf Fabric | 2 layers (Spine + Leaf) | Google, Facebook, big data centers | If you do data centers | Very hot in 2025 |