If the internet sometimes feels like a silent, invisible river of information, this subject is where you learn to see the currents, the bridges, and the locks that make it all flow. Data Communications and Computer Networks isn’t just about memorizing acronyms; it’s the masterclass on how the digital world actually talks. This past paper is your chance to prove you don’t just use the network—you understand its language.
Forget dry theory. This exam throws you into the lifecycle of a single packet—from the electrical pulse in a wire to the webpage on your screen. It’s a story in layers, and you need to know every chapter.
What This Paper Covers: The Journey of a Packet
1. The Physical Whisper: From Signal to Bit
It all starts here. Questions dive into how ones and zeros become voltage, light, or radio waves. You’ll tackle:
- Transmission Media: Copper, fiber, wireless—and why you’d choose one over another.
- Encoding Schemes (like Manchester or NRZ-I) that keep sender and receiver in sync.
- Error Detection & Correction: CRCs, parity checks—the “spell-check” for data.
It’s not just trivia. A question might ask: “Calculate the maximum data rate for this channel using Nyquist’s theorem.” This is the physics of communication, and it sets the stage for everything else.
2. The Local Chat: LANs and Switching
Here, data learns to find its way around a neighborhood. You’ll face:
- Ethernet frames, MAC addresses, and switches—the “who” and “where” of local delivery.
- ARP protocols that translate IPs to MACs.
- Classic problems like collision domains and how switches eliminate them.
This section feels practical because it is—misconfigure a switch, and the whole office goes quiet.
3. The Global Postal System: Routing and The Internet Layer
This is the brain of the network. Be ready for:
- IP Addressing & Subnetting: Guaranteed to appear. You’ll be asked to subnet an address space for a company with multiple departments. Speed and accuracy here are non-negotiable.
- Routing Algorithms: Distance vector (RIP) vs. link state (OSPF)—not just their rules, but their trade-offs in speed, stability, and overhead.
- The journey of a packet across routers, with questions on TTL, fragmentation, and routing tables.
This is where you move from local chat to global conversation.
4. The Reliable Courier vs. The Speedy Postcard: Transport Layer
TCP vs. UDP isn’t just a choice—it’s a philosophy. The paper tests deep understanding:
- TCP’s reliability: The three-way handshake, sequence numbers, flow control (sliding windows), and congestion control (AIMD, slow start).
- Scenario: “Why would a video streaming service use UDP, and how does it handle packet loss?”
- You might need to sketch a TCP state diagram or analyze a trace of a conversation.
5. The Applications & The Guardians: Top Layers and Security
Finally, data becomes useful. DNS, HTTP, SMTP, FTP—the services we actually interact with. But layered throughout are questions of security:
- “Where does SSL/TLS operate, and what does it protect?”
- “How does a firewall differ from an intrusion detection system?”
- Security is framed not as an add-on, but as a core design constraint, from physical layer encryption to application-layer HTTPS.
The Paper’s Real Test: Systems Thinking
The biggest challenge? No concept is isolated. A question might start with an IP address, move to a routing protocol, touch on TCP congestion, and end with a DNS query. You need to see the entire stack working together.
How to Use This Past Paper Effectively:
- Subnet in Your Sleep.
Drill subnetting daily until it’s muscle memory. Exam pressure turns hesitation into mistakes. - Draw the Conversations.
For any protocol (DHCP, TCP, ARP), sketch the message exchange between devices. A visual story is unforgettable. - Adopt a Troubleshooter’s Mindset.
Use the layers: “Can’t connect? Is it the cable (L1)? The MAC address (L2)? The IP config (L3)? The firewall rule (L4)? The server service (L7)?” - Relate Everything to Reality.
When studying routing, think of the internet as a map. When studying TCP, think of it as a careful, confirming conversation. Anchor each protocol in a real-world analogy.
This past paper is more than a revision tool—it’s a litmus test for your systems understanding. It asks: Can you see the matrix? Can you trace a cat video from a server in another continent to your screen, through all its twists and turns? If you can, you’re not just passing an exam; you’re building the mindset of a network engineer, architect, or guardian of the digital world.
Final question paper 2020
Q.1:
a) Write down the properties of Fiber-Optic cable
b) Construct (15, 11) Hamming code for the message 11010010100 by considering even parity.
Q.2:
a) Brietly explains Virtual-Circuit Networks (6)
b) Construct a cyclic code (7, 4) using the generator polynomial G(x)=x3+x+1, Consider a data vector d = 1001.
Q.3:
a) Ixplains the different types of Data Link Layer Protocols. b) Write the characteristics of standard ETHERNET. (7)
Describes the concept of Random Access Media Access Control (MAC). b) Write the note on Frequency Division Midtiplexing with diagrams and examples. (6)
Sessional 2 2020
Q.1:
a) Briefly explain Quadrature Amplitude Modulation (QAM). What are the limitations in other types of digital to analog conversion techniques and how these limitations overcome by QAM? (4
b) Differentiate between Pulse Code Modulation and Delta Modulation. Which technique is better and why?
Q.2:
a) Assume that a voice channel occupies a bandwidth of 4 KHz. We need to combine four voice channels into a link with a bandwidth of 16 kHz, from 30 to 46 kHz. Show the configuration, using the frequency domain. Assume there are no guard bands. (3.5)
b) Draw the diagram of the following bit pattern by using HDB3 Scrambling technique: (4
Sessional 1 2020
Q.1: Give the short answers of the followings:
1. What is mean by Jitter?
II. What is mean by Signal-to-Noise Ratio (SNR)
Draw the figure for AMI and pseudoternary Bipolar scheme of the following message: 00110100110
Q.2: (1+3)
a) Demonstrates the concept “effect of lack of synchronization” with the help of diagr.
b) Briefly explains the Network and Transport layer of Internet protocol suite.
Q.3: What is the difference between “Non-Return-to-Zero (NRZ)” and “Return-to-Zero (RZ)”? Thoroughly explain with examples and diagrams. What are the schemes used to handles the problems encountered in NRZ?
Mid term Examination 2021
Q.No.1
Draw the graph of the HDB3 scrambling scheme using the following data streams:
10110000010011000001010000010
Q.No.2
Assume that a voice channel occupies a bandwidth of 4KHZ.we need to multiplex voice channels with guard bands of 500Hzusing FDM. Calculate the required bandwidth.
Q.No.3
Discuss the types of transmission impairment.
Q.No.4
Which of the four digital-to-analog conversion techniques (ASK, FSK, PSK AND QAM) is the most susceptible to noise? Defend your answer.