Key takeaways
- Subnetting, sliding window efficiency, CRC and TCP congestion are the main numericals.
- Learn common port numbers and the 3-way handshake for quick short answers.
- Each section has exam tips and formula boxes, and the last page lists the most asked practice questions.
- These are original Uncodemy revision notes, not official university notes; check your own syllabus.
About these Computer Networks handwritten notes
This page offers Uncodemy's Computer Networks notes as a free handwritten-style PDF. Computer Networks explains how data moves between computers, layer by layer, from bits on a wire to applications such as the web and email. The notes are written in short points with neat tables, labelled diagrams, boxed formulas and exam tips, so you can revise a full unit in one sitting instead of reading a long textbook chapter.
Please note: these are original Uncodemy revision notes. They follow the common syllabus that most Indian universities share for this subject, but they are not official university notes. Check your own university syllabus and add anything it lists that is missing here.
What's inside the Computer Networks notes
The PDF is arranged in 8 sections plus a final page of most asked practice questions. The sections follow the usual unit order of a Computer Networks syllabus, so you can map them to your own units quickly. Here is what each section covers.
Introduction and reference models
Network types and topologies, and the OSI and TCP/IP models compared layer by layer.
Physical layer and delays
Transmission media, bandwidth, and transmission, propagation, queuing and processing delay with formulas.
Data link layer
Framing, error detection with parity, checksum and CRC, Hamming code, Stop-and-Wait, Go-Back-N and Selective Repeat, and medium access with ALOHA and CSMA/CD.
Network layer: IP addressing
IPv4 classes, CIDR subnetting with a solved example for network, broadcast and host range, plus ARP, ICMP, NAT and IPv6 basics.
Routing
Distance vector and link state routing, the count-to-infinity problem, and protocols such as RIP, OSPF and BGP.
Transport layer
TCP vs UDP, the TCP header and 3-way handshake, flow control, and TCP congestion control with slow start and congestion avoidance.
Application layer
DNS, HTTP, SMTP, FTP and DHCP, and the port numbers you need to remember.
Network security basics
Firewalls, encryption, VPNs and the common attacks on networks.
Most asked questions (practice)
Ten exam-style questions, from OSI vs TCP/IP to Hamming code.
How to use handwritten notes to revise Computer Networks
Computer Networks combines layer-wise theory with formula-based numericals, so keep a separate formula page while you revise from the notes.
- Write all delay, efficiency and window size formulas on one page and practise one problem for each.
- Solve three CIDR subnetting questions a day until network and broadcast addresses come quickly.
- Draw the TCP congestion window graph with slow start, threshold and congestion avoidance.
- Revise the OSI layers with one protocol and one device for each layer.
A simple three-pass method works well with handwritten notes. In the first pass, read one section and underline only what you do not already know. In the second pass, close the notes and write the definitions, diagrams and steps for that section on a blank sheet, then compare and correct in a different colour. In the third pass, a day or two later, answer two or three exam-style Computer Networks questions in timed conditions using only memory. Add your own examples and doubts in the margins so the PDF becomes your personal revision copy.
Formulas, diagrams and definitions to memorise
- Transmission delay = packet size / bandwidth, and propagation delay = distance / propagation speed.
- Stop-and-Wait efficiency = 1 / (1 + 2a), where a = propagation delay / transmission delay.
- Pure ALOHA maximum throughput of about 18.4% and slotted ALOHA of about 36.8%.
- Number of hosts in a subnet = 2 to the power of host bits, minus 2.
- The OSI and TCP/IP layer diagram side by side, and common port numbers such as HTTP 80, HTTPS 443, DNS 53 and SMTP 25.
Common mistakes that cost marks
- Counting the network and broadcast addresses as usable hosts.
- Mixing up the window size limits for Go-Back-N and Selective Repeat.
- Appending the wrong number of zeros before CRC division; append degree-of-generator zeros.
- Drawing the TCP congestion graph without marking the threshold and the point of loss.
Exam focus: Computer Networks topics that carry the most marks
Computer Networks papers mix layer theory with numericals. These topics carry the most marks.
- OSI vs TCP/IP models.
- CRC, Hamming code and sliding window efficiency.
- IP addressing and subnetting.
- Routing algorithms, TCP congestion control and DNS.
Typical long questions
- Explain the OSI and TCP/IP models and compare them.
- Find the CRC for given data and a generator polynomial.
- Compare Stop-and-Wait, Go-Back-N and Selective Repeat and find their efficiency.
- Derive the efficiency of pure and slotted ALOHA.
- Find the network address, broadcast address and host range for a CIDR block.
- Compare distance vector and link state routing.
- Explain TCP slow start and congestion avoidance with a graph.
Marks per question change between universities and years, so confirm the pattern on a recent official paper. In long answers, start with a definition, add a labelled diagram or table, explain the steps and finish with an example or comparison. Underline the key term in each answer and leave a line between steps, because examiners mark faster when the structure is easy to see.
A 7-day revision plan for Computer Networks
- Day 1: Introduction and reference models, Physical layer and delays.
- Day 2: Data link layer, Network layer: IP addressing.
- Day 3: Routing, Transport layer.
- Day 4: Application layer.
- Day 5: Network security basics.
- Day 6: redo the numericals: CRC, Hamming code, sliding window efficiency, ALOHA throughput and two subnetting problems.
- Day 7: answer the most asked practice questions at the end of the notes from memory, then solve one official previous year paper in three hours and mark the units that cost you time.
Keep a single sheet of formulas, definitions and diagrams from the notes for the last hour before the exam, and do not start new topics on the final day.
Who these notes are for
- B.Tech CSE, IT and ECE students preparing for the semester Computer Networks exam.
- BCA and MCA students with a data communication or networks paper.
- GATE CS aspirants revising the CN numericals listed above.
- Freshers preparing for networking, cloud, DevOps or support role interviews.
The notes are a revision aid, not a first textbook. If a Computer Networks topic is new to you, learn it from your prescribed book or class lectures first, then come back to the notes to compress and revise it. For practice, pair them with the Computer Networks Important Questions PDF page and your university's official previous year papers. If your syllabus has a topic that is not covered here, you can ask for it through the handwritten notes request page linked below.
Download Computer Networks Handwritten Notes PDF
Computer Networks Handwritten Notes PDF (Free)
The PDF carries the same content as this page in a clean, print-ready layout, so you can read it offline and keep it for revision.
7 pages · 277 KB · PDF · Updated 5 Nov 2026