Computer Networks Basics (OSI Layers, IP Addressing)

Learn core concepts, essential formulas, and attempt practice questions designed on the latest TCS NQT testing patterns.

Key Concepts & Formulas

1OSI Model: 7 Layers (Physical, Data Link, Network, Transport, Session, Presentation, Application).
2IP Classes: Class A (0-127), Class B (128-191), Class C (192-223).
3TCP (Connection-oriented) vs UDP (Connectionless).

Practice Question 1

At which layer of the OSI model does a router operate?

A) Network Layer

B) Physical Layer

C) Data Link Layer

D) Transport Layer

Correct Answer: A) Network Layer

Step-by-step Solution: Routers forward packets across networks, operating at the Network Layer (Layer 3).

Practice Question 2

What class is the IP address 192.168.1.1?

A) Class C

B) Class A

C) Class B

D) Class D

Correct Answer: A) Class C

Step-by-step Solution: 192 lies in the range 192-223, making it a Class C address.

Use the mnemonic 'Please Do Not Throw Sausage Pizza Away' to remember OSI layers (Physical to Application).