CyberCertPrepNetwork FundamentalsOSI & TCP/IP ModelsEASYFree question
What is the key functional difference between the OSI model and the TCP/IP (DoD) model in terms of number of layers and how they map?
- A.The TCP/IP model has 7 layers just like OSI but names them differently
- B.The TCP/IP model has 4 layers: Network Access (≈OSI L1+L2), Internet (≈OSI L3), Transport (≈OSI L4), Application (≈OSI L5+L6+L7) - it collapses OSI layers 1-2 and 5-7
- C.The TCP/IP model has 5 layers and maps one-to-one with OSI layers 1-5
- D.OSI and TCP/IP are identical; the names are just different countries' preferences
Why B is correct
The TCP/IP model (also called DoD or DARPA model) has 4 layers: (1) Network Access / Link - combines OSI Physical + Data Link. (2) Internet - OSI Network (IP, ICMP, ARP). (3) Transport - OSI Transport (TCP, UDP). (4) Application - combines OSI Session + Presentation + Application (HTTP, DNS, FTP, SMTP, etc.). This is why OSI is the 'reference model' for teaching and TCP/IP is the implemented model for real-world networking.
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