Suggest an editImprove this articleRefine the answer for “Why is TCP/IP a practical model?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**TCP/IP** is considered a practical model because, unlike OSI, which is just a concept, it describes protocols that actually exist, a set of working standards used every day across the internet, data centers, and home networks. **Key point:** TCP/IP worked first as part of ARPANET and was only later described as a model.Shown above the full answer for quick recall.Answer (EN)Image## **Why TCP/IP is considered a practical model** ### **1. TCP/IP describes protocols that actually exist** OSI is a concept. TCP/IP is a *set of working standards*. TCP/IP protocols are used every day: - across the entire internet - in data centers - in home networks - in Wi-Fi and mobile networks It is not a scheme but a **ready-made toolkit**. --- ### **2. TCP/IP existed in practice before it was formalized** TCP/IP began development in the 1970s as part of ARPANET. It **worked first**, and only later was it described as a model. In other words, the model was created **to explain a reality that already existed**, not the other way around. --- ### **3. TCP/IP is used in every operating system** Every modern operating system already includes the TCP/IP stack: - Windows - Linux - macOS - Android - iOS - network equipment (Cisco, Juniper, MikroTik...) When you turn on your computer and connect to the internet, you are using TCP/IP. --- ### **4. TCP/IP became the foundation of the internet** All the key internet protocols are TCP/IP protocols: - **IP** - routing - **TCP** - reliable transport - **UDP** - fast transport - **DNS** - domain names - **HTTP/HTTPS** - the web - **ICMP** - diagnostics (ping) - **BGP/OSPF** - routing between networks That is exactly why the internet = TCP/IP. --- ### **5. TCP/IP was built by engineers for real-world tasks** From its inception, the focus was on: - **reliability in real networks** - **operation under failure conditions** - **scalability** - **simplicity of implementation** - **minimal hardware requirements** This is exactly what a practical network needs. --- ### **6. TCP/IP is a flexible, minimalistic, and easy-to-implement model** Unlike OSI, where the 7 layers are strictly separated, TCP/IP: - merges OSI layers 5-7 into one **Application** - merges OSI layers 1-2 into **Network Access** - does not introduce redundant abstractions - does not force vendors to strictly conform to the layers This makes it **easy to implement** and adapt. --- ### **7. TCP/IP is backed by IETF standards** TCP/IP standards are RFCs: - open - flexible - widely applicable It is a living stack that keeps evolving: - IPv6 - QUIC - HTTP/3 This is another sign of its *practicality*. --- ## Summary: what's the point? TCP/IP is a practical model because: - it describes **how networks actually work**, not how they should work - its protocols are **not theory but real software, firmware, and hardware** - it is the foundation of the internet - every network device operates according to TCP/IP OSI is an educational scheme. TCP/IP is the real world. --- ## **Ready answer for an interview** > **TCP/IP is a practical model because it describes the real protocol stack that is actually used in modern networks and the internet.** > **It is not a theoretical scheme but a set of working technologies, TCP, UDP, IP, DNS, HTTP, ICMP, and others, implemented in operating systems, routers, and network equipment.** > **The model arose from practice and serves as the foundation of the global Internet.**For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.