# Q1B · TCP/IP reference model

Subject: Computer Networks

Exam: TEE

Reader: https://deep-learning-study-room.vercel.app/cn/#tee/papers/tee-paper-reexam/q1b

Canonical: https://deep-learning-study-room.vercel.app/read/cn/tee/papers/tee-paper-reexam--q1b/

TEE · Actual TEE paper · all questions · current syllabus 702AI0C023

### Actual PYQ · Q1B. Draw the labelled diagram of the TCP/IP reference model and explain the task of all layers. [5 marks]

#### Answer

Swipe across the diagram to read its labels ↔

![OSI layers mapped to the four-layer TCP/IP model](https://deep-learning-study-room.vercel.app/cn/fig/tee-models.5bff0518c8.svg)

Diagram: OSI layers mapped to the four-layer TCP/IP model. Labels: OSI layers mapped to the four-layer TCP/IP model | OSI layers mapped to the four-layer TCP/IP model | 7 Application | 6 Presentation | 5 Session | 4 Transport | 3 Network | 2 Data link | 1 Physical | Application | HTTP, DNS, FTP, SMTP | Transport | Internet | Link / network access | Includes physical access | Some textbooks split link into data link + physical: five layers.

TCP/IP model and its OSI mapping.

| Layer | Task | Examples |
| --- | --- | --- |
| Application | Defines application message formats and exchanges for Web access, naming, email and file transfer; includes presentation/session functions as needed | HTTP, DNS, SMTP, FTP |
| Transport | End-to-end process communication | TCP, UDP, SCTP |
| Internet | IP addressing, routing and best-effort datagrams | IPv4/IPv6 |
| Link/network access | Local delivery and physical access | Ethernet/Wi-Fi and their medium |

Here the four-layer convention includes physical access within the link layer. A five-layer textbook diagram may split physical from data link; label which convention is being used.

#### Practical example

An HTTP request goes through application → transport TCP → internet IP → link Ethernet/Wi-Fi. Each layer contributes a different delivery function.

Source: Re-exam · 4 February 2026, original question paper page 1. Original marks retained; solution independently authored.