Computer Networks Practice Questions With Answers: MCQs, Short & Long Questions
Computer Networks can look easy while reading notes, but the real test comes when you try to answer questions without looking at the chapter. Students often remember the name of a protocol but forget its working, confuse one OSI layer with another, or understand subnetting in theory but struggle when the same concept appears differently in an exam.
That is why this page is designed as a complete Computer Networks practice set instead of another set of notes. You will find MCQs for concept checking, short questions for quick written practice and long questions with detailed answers that help you prepare for university semester exams.
How to Practise Computer Networks Questions Properly
Different questions test different levels of understanding. Use a different strategy for MCQs, short answers and long answers.
Check Concept Accuracy
Do not guess only from familiar words. Read all four options and identify exactly which layer, protocol, address or network function the question is testing.
Answer Directly
Start with the definition and then write the most important functions, differences, advantages or working steps. Avoid unrelated theory.
Write in Structure
Use introduction, headings, working, diagrams, comparisons, advantages or limitations and a short conclusion wherever the question needs them.
Computer Networks Complete 37-Chapter Study Map
Every major practice topic on this page is connected with the detailed Computer Networks lessons on SahilDubey.com.
Computer Networks MCQs With Answers
Try to solve every question before opening the answer. These questions focus on concepts that are commonly confused during exams.
1. Which OSI layer is responsible for routing packets between different networks?
The Network Layer performs logical addressing, routing and packet forwarding between different networks.
2. Which topology connects every device to a central networking device?
In a star topology, each end device connects to a central hub or switch.
3. Which transmission medium carries information using light?
Optical fibre carries digital information in the form of light signals.
4. Which switching technique establishes a dedicated path before communication?
Circuit switching establishes and reserves a communication path before data transfer begins.
5. ISDN stands for:
6. Which sublayer controls access to a shared transmission medium?
The Media Access Control sublayer decides how devices access a shared network medium.
7. In Pure ALOHA, a station can transmit:
8. IEEE 802.3 is mainly associated with:
9. IEEE 802.11 is mainly associated with:
10. FDDI traditionally uses which topology?
11. Which layer performs framing?
12. Flow control is mainly used to prevent:
Flow control prevents a fast sender from overwhelming a slower receiver.
13. ARQ stands for:
14. Which ARQ protocol retransmits a group of outstanding frames after a missing frame?
15. Which protocol retransmits only the required missing or damaged frames?
16. CRC is mainly used for:
17. Hamming Code is capable of correcting:
18. Which device mainly forwards packets between IP networks?
19. PPP stands for:
20. Which routing technique commonly exchanges route information with neighbouring routers?
21. Which routing technique creates a topology database of network links?
22. Network congestion occurs when:
23. Tunneling means:
24. IPv4 uses addresses of:
25. IPv6 uses addresses of:
26. CIDR stands for:
27. The notation /24 indicates:
28. TTL in IPv4 is mainly used to:
29. Which IPv4 field helps identify fragments belonging to the same original datagram?
30. Which model is used by the Internet protocol architecture?
31. The Transport Layer provides:
32. Which transport protocol is connection-oriented?
33. Which protocol has lower transport-layer overhead and is connectionless?
34. The first message in the TCP three-way handshake normally contains:
35. TCP receiver window is primarily associated with:
36. TCP congestion window mainly responds to:
37. Which OSI layer manages sessions and synchronization?
38. RPC stands for:
39. The Presentation Layer commonly deals with:
40. Symmetric encryption normally uses:
41. Asymmetric cryptography uses:
42. Hashing is generally designed to be:
43. Which of the following is associated with file transfer?
44. The Application Layer is:
45. Which concept divides one IP network into smaller logical networks?
46. Which term describes connecting different independent networks?
47. Which layer contains IP in the TCP/IP model?
48. Which technique is more efficient than Pure ALOHA because transmission begins only at slot boundaries?
49. Which concept mainly protects the network rather than only the receiver?
50. The Internet can best be described as:
The Internet connects a very large number of independently managed networks through common protocols and routers.
Computer Networks Short Questions With Answers
These questions are useful for 3-mark and 5-mark practice. Write definitions first and then explain the main points clearly.
1. What is a computer network? Explain its main goals.
A computer network is a collection of interconnected computers and devices that communicate and share information, resources and services.
Main goals include:
- Resource sharing.
- Communication between users.
- Data sharing.
- Remote access.
- Improved reliability.
- Distributed processing.
2. What is network architecture?
Network architecture describes the overall organisation of a computer network. It explains how network components, protocols, layers and services are arranged and how they communicate.
An architecture normally defines:
- Communication layers.
- Protocols used at different levels.
- Services offered by each layer.
- Relationship between network devices and software.
3. Explain the purpose of the OSI model.
The OSI model divides network communication into seven logical layers. Each layer has a specific responsibility.
Its main purposes are:
- To make network communication easier to understand.
- To separate complex networking tasks into smaller functions.
- To help different technologies work through standard interfaces.
- To simplify troubleshooting.
- To support modular protocol design.
4. Differentiate between star and mesh topology.
| Point | Star | Mesh |
|---|---|---|
| Structure | Devices connect to a central device | Devices have multiple direct links |
| Cost | Moderate | High |
| Reliability | Depends heavily on central device | High due to alternative paths |
| Complexity | Simple | More complex |
5. Explain guided and unguided transmission media.
Guided media carries signals through a physical path. Examples include twisted-pair cable, coaxial cable and optical fibre.
Unguided media carries signals through free space without a physical conductor. Examples include radio waves, microwave and satellite communication.
6. Differentiate between circuit and packet switching.
Circuit switching creates a dedicated communication path before transmission. Packet switching divides information into packets and shares communication links with other users.
- Circuit switching reserves resources.
- Packet switching shares resources dynamically.
- Packet switching is suitable for bursty computer traffic.
- Circuit switching traditionally suits continuous communication.
7. What are B and D channels in ISDN?
In ISDN:
- B Channel: Bearer channel used for carrying user information such as voice or data.
- D Channel: Mainly carries signalling and control information.
8. Explain important functions of terminal handling.
- Accepting terminal input.
- Displaying or echoing typed characters.
- Buffering data temporarily.
- Controlling data flow.
- Polling terminals for data.
- Selecting terminals for communication.
- Supporting terminal emulation.
9. What are the main functions of the MAC sublayer?
- Controls access to the shared medium.
- Uses MAC addresses.
- Supports local frame transmission.
- Coordinates multiple devices competing for the same channel.
- May support collision-related mechanisms depending on the network technology.
10. Differentiate between static and dynamic channel allocation.
In static allocation, channel capacity is divided in advance and remains allocated even if a station has no data.
In dynamic allocation, channel access is assigned according to current traffic demand.
Dynamic allocation is generally better for bursty traffic because unused capacity can be shared more efficiently.
11. Compare Pure ALOHA and Slotted ALOHA.
- Pure ALOHA allows transmission at any time.
- Slotted ALOHA allows transmission only at slot boundaries.
- Pure ALOHA has a larger vulnerable period.
- Slotted ALOHA reduces collision probability.
- Slotted ALOHA provides better maximum efficiency.
12. What are IEEE 802.3 and IEEE 802.11?
IEEE 802.3 is associated with Ethernet-based wired LAN technologies.
IEEE 802.11 defines wireless LAN standards commonly used for Wi-Fi communication.
13. Explain FDDI briefly.
FDDI stands for Fiber Distributed Data Interface. It is a high-speed network technology traditionally based on optical fibre.
Its important characteristics include:
- Dual-ring architecture.
- Token-based access.
- High reliability.
- Secondary ring for fault tolerance.
14. Explain the main functions of the Data Link Layer.
- Framing.
- Physical addressing.
- Flow control.
- Error control.
- Access control on shared media.
- Reliable node-to-node delivery where supported by the protocol.
15. What is Stop-and-Wait ARQ?
In Stop-and-Wait ARQ, the sender transmits one frame and waits for acknowledgement before sending the next frame.
If acknowledgement does not arrive before timeout, the sender retransmits the frame. Sequence numbers help identify duplicate frames.
16. Differentiate between Go-Back-N and Selective Repeat.
- Go-Back-N retransmits the missing frame and later outstanding frames.
- Selective Repeat retransmits only required frames.
- Go-Back-N receiver logic is simpler.
- Selective Repeat requires more buffering.
- Selective Repeat can be more efficient when errors occur.
17. Explain CRC.
CRC stands for Cyclic Redundancy Check. It is an error-detection technique based on modulo-2 division.
- Data is treated as a binary polynomial.
- A generator polynomial is selected.
- The sender calculates a remainder.
- The remainder is attached to the frame.
- The receiver performs the same division.
- A non-zero remainder normally indicates an error.
18. Explain Hamming Code.
Hamming Code adds redundant parity bits at positions such as 1, 2, 4 and 8.
These parity bits check different combinations of data bits. At the receiver, the parity results form a syndrome that identifies the position of a single-bit error.
For m data bits and r redundant bits:
2r ≥ m + r + 1
19. Explain the functions of the Network Layer.
- Logical addressing.
- Routing.
- Packet forwarding.
- Internetworking.
- Fragmentation-related processing where needed.
- Supporting network traffic management.
20. What is PPP?
PPP stands for Point-to-Point Protocol. It is used for communication between two directly connected network nodes.
Main features include:
- Link configuration.
- Framing.
- Error detection.
- Support for authentication.
- Support for multiple Network Layer protocols.
21. Compare Distance Vector and Link State routing.
| Point | Distance Vector | Link State |
|---|---|---|
| Knowledge | Distance and next-hop information | Network topology information |
| Exchange | Usually with neighbours | Link-state information is distributed |
| Complexity | Lower | Higher |
| Convergence | May be slower | Often faster |
22. What is congestion? Mention its effects.
Congestion occurs when traffic entering the network becomes greater than the available network resources.
Effects include:
- Long queueing delay.
- Packet loss.
- Retransmissions.
- Lower useful throughput.
- Poor application performance.
23. Explain tunneling.
Tunneling is a technique in which one protocol packet is encapsulated inside another protocol packet so that it can cross an intermediate network.
At the tunnel entrance, an outer header is added. At the tunnel exit, the outer header is removed and the original packet continues toward its destination.
24. Differentiate between OSI and TCP/IP models.
- OSI has seven layers.
- TCP/IP is commonly represented with four layers.
- OSI is mainly a reference model.
- TCP/IP represents the Internet protocol architecture.
- OSI has separate Session and Presentation Layers.
- TCP/IP normally combines these functions into its Application Layer.
25. Explain the important fields of an IPv4 header.
- Version.
- Internet Header Length.
- Total Length.
- Identification.
- Flags.
- Fragment Offset.
- Time To Live.
- Protocol.
- Header Checksum.
- Source Address.
- Destination Address.
26. What is subnetting?
Subnetting divides one IP network into smaller logical networks.
Bits are borrowed from the host portion and used to create additional network prefixes.
Subnetting improves address organisation, network management and routing structure.
27. Compare IPv4 and IPv6.
- IPv4 uses 32-bit addresses.
- IPv6 uses 128-bit addresses.
- IPv4 uses dotted-decimal notation.
- IPv6 uses hexadecimal notation.
- IPv6 provides a much larger address space.
- IPv6 uses a simplified fixed-size base header.
28. Explain Transport Layer functions.
- Process-to-process communication.
- Port addressing.
- Segmentation and reassembly.
- Multiplexing and demultiplexing.
- Connection management.
- Flow control.
- Reliable delivery and error recovery where supported.
29. Compare TCP and UDP.
TCP is connection-oriented and provides reliable ordered delivery using acknowledgements, sequence numbers and retransmission.
UDP is connectionless and has lower overhead, but it does not provide TCP-style reliable ordered delivery.
30. Explain symmetric, asymmetric encryption and hashing.
- Symmetric encryption: Same secret key is used for encryption and decryption.
- Asymmetric encryption: Uses a public and private key pair.
- Hashing: Converts input into a fixed-size digest using a one-way function.
Encryption mainly protects confidentiality, while hashing is widely used for integrity verification and related security applications.
Computer Networks Long Questions With Detailed Answers
These are suitable for long university-exam questions. Practise the structure, not only the wording.
1. Explain the OSI model in detail with functions of all seven layers.
Introduction
The OSI model, or Open Systems Interconnection model, is a seven-layer reference model developed to explain network communication in a structured way. Each layer performs specific functions and provides services to the layer above it.
1. Physical Layer
The Physical Layer transmits raw bits over the communication medium. It deals with signals, connectors, bit rate, transmission media and physical network interfaces.
2. Data Link Layer
The Data Link Layer provides node-to-node communication. Its important functions include framing, MAC addressing, flow control, error control and medium access.
3. Network Layer
The Network Layer provides logical addressing, routing and packet forwarding. Routers mainly operate at this layer.
4. Transport Layer
The Transport Layer provides process-to-process communication. It performs segmentation, reassembly, port addressing, multiplexing, connection management and reliability where required.
5. Session Layer
The Session Layer establishes, maintains and terminates sessions between communicating applications. It also supports dialogue control and synchronization.
6. Presentation Layer
The Presentation Layer deals with data representation. It can perform format translation, character-code conversion, compression and other data transformations.
7. Application Layer
The Application Layer provides network services directly to user applications. File transfer, email, web access and remote terminal services are examples of application-level network services.
Advantages of the OSI Model
- Divides complex networking into manageable layers.
- Helps understand protocol responsibilities.
- Makes troubleshooting easier.
- Supports modular network design.
- Provides a common language for discussing networking.
Conclusion
The OSI model is important because it explains the complete network communication process from physical transmission to application-level services in seven clear layers.
2. Explain different network topologies with advantages and disadvantages.
Introduction
Network topology represents the physical or logical arrangement of network devices and communication links.
Bus Topology
All devices share one main communication cable called the backbone.
Advantages:- Simple design.
- Lower cable requirement for small networks.
- Low initial cost.
- Backbone failure affects communication.
- Fault detection can be difficult.
- Performance decreases when traffic becomes high.
Star Topology
Every device connects to a central hub or switch.
Advantages:- Easy installation.
- Easy fault isolation.
- Failure of one end-device cable normally affects only that device.
- Central-device failure can stop communication.
- Requires more cable.
Ring Topology
Devices are connected in a circular communication path.
Advantages:- Organised access.
- Predictable communication path.
- A break can affect a simple ring.
- Adding or removing devices can be more difficult.
Mesh Topology
Devices are connected using multiple direct links.
Advantages:- High reliability.
- Alternative communication paths.
- Good fault tolerance.
- High cost.
- Complex installation.
Tree Topology
Tree topology uses a hierarchical structure and is useful for larger organised networks.
Hybrid Topology
A hybrid topology combines two or more topology types according to practical network requirements.
Conclusion
Topology selection depends on cost, reliability, performance, network size, scalability and maintenance requirements.
3. Explain transmission media in detail and compare guided and unguided media.
Introduction
Transmission media is the path through which communication signals travel between network devices.
Guided Media
Guided media carries signals through a physical path.
Twisted-Pair Cable
Two copper wires are twisted together to reduce interference. It is inexpensive and widely used in telephone and Ethernet networks.
Coaxial Cable
Coaxial cable contains a central conductor, insulation and shielding. It provides better protection from interference than simple unshielded copper wiring.
Optical Fibre
Optical fibre transmits information using light. It provides high bandwidth, long-distance communication and strong resistance to electromagnetic interference.
Unguided Media
Unguided media sends signals through free space.
Radio Waves
Radio communication supports wireless transmission and can provide broad coverage.
Microwave
Microwave communication supports high-capacity wireless links and commonly requires suitable line-of-sight conditions for terrestrial communication.
Satellite Communication
Satellites can provide communication over very large geographical areas.
| Point | Guided | Unguided |
|---|---|---|
| Medium | Physical conductor | Free space |
| Examples | Twisted pair, coaxial, fibre | Radio, microwave, satellite |
| Mobility | Lower | Higher |
| Interference | Depends on cable; fibre is highly resistant | Wireless signals may face interference |
Conclusion
The correct transmission medium depends on distance, bandwidth, cost, mobility, reliability and the physical environment.
4. Explain circuit switching, message switching and packet switching.
Circuit Switching
Circuit switching creates a dedicated communication path between sender and receiver before data transfer begins.
It provides a continuous path but may waste capacity when no data is being transmitted.
Message Switching
The complete message is stored at an intermediate node and later forwarded to the next node. This is called store-and-forward communication.
It does not need a dedicated path but can create high delay and requires large storage.
Packet Switching
The message is divided into small packets. Packets travel through the network and are reassembled at the destination.
Advantages include:
- Efficient sharing of communication links.
- Good support for bursty traffic.
- Many users can share network resources.
Conclusion
Modern computer networks mainly use packet switching because it allows network resources to be shared efficiently.
5. Explain MAC sublayer, channel allocation, Pure ALOHA and Slotted ALOHA.
MAC Sublayer
The Media Access Control sublayer controls how network devices use a shared communication channel.
Main functions include:
- MAC addressing.
- Medium access control.
- Local frame transmission.
- Coordination between competing stations.
Static Channel Allocation
Channel capacity is divided in advance between users. Capacity may remain unused when a user has no data.
Dynamic Channel Allocation
Channel access is assigned according to traffic demand. It is more suitable for bursty computer traffic.
Pure ALOHA
- A station transmits whenever it has data.
- Frames may collide.
- After collision, the station waits a random time before retransmission.
Slotted ALOHA
- Time is divided into fixed slots.
- Transmission starts only at a slot boundary.
- The vulnerable period is smaller.
- Efficiency is better than Pure ALOHA.
Conclusion
MAC protocols are necessary because many devices may need the same channel at the same time. Dynamic access protocols help share this medium efficiently.
6. Explain Sliding Window Protocol, Go-Back-N and Selective Repeat ARQ.
Introduction
Sliding Window Protocol allows multiple frames to be transmitted before every individual acknowledgement is received. This improves network utilisation compared with simple Stop-and-Wait communication.
Basic Working
Frames use sequence numbers. The sender maintains a sender window containing frames that may be transmitted. As acknowledgements arrive, the window moves forward.
Go-Back-N ARQ
- Sender may transmit several frames.
- Receiver normally expects the next frame in sequence.
- Out-of-order frames are usually discarded.
- If one frame is lost, that frame and later outstanding frames may be retransmitted.
For m sequence-number bits, the classical sender-window condition is:
W ≤ 2m - 1
Selective Repeat ARQ
- Receiver can buffer out-of-order frames.
- Only required frames are retransmitted.
- Better efficiency during errors.
- Requires more memory and complex control.
A common Selective Repeat window condition is:
W ≤ 2(m-1)
Conclusion
Go-Back-N is simpler, while Selective Repeat uses bandwidth more efficiently when errors occur frequently.
7. Explain Parity, Checksum, CRC and Hamming Code.
Introduction
Data may be corrupted during transmission because of noise and communication problems. Error-detection and correction techniques add redundant information to help identify or repair errors.
Parity
A parity bit is added to make the total number of 1s even or odd.
- Even parity makes the number of 1s even.
- Odd parity makes the number of 1s odd.
Checksum
The sender divides data into words and performs an arithmetic calculation to generate a checksum. The receiver repeats the calculation to check whether data was corrupted.
CRC
Cyclic Redundancy Check uses modulo-2 division.
- Select a generator polynomial.
- Append zeros to the original data.
- Perform modulo-2 division.
- Attach the remainder.
- Receiver performs the same division.
Hamming Code
Hamming Code places redundant bits at power-of-two positions.
The redundancy condition is:
2r ≥ m + r + 1
The receiver uses parity checks to calculate an error syndrome and can correct one incorrect bit.
Conclusion
Parity and checksum provide simple error detection, CRC gives strong detection capability, and Hamming Code adds error-correction ability.
8. Explain the Network Layer and Distance Vector and Link State routing.
Network Layer
The Network Layer provides logical addressing and packet delivery across different networks.
Main functions include:
- Logical addressing.
- Routing.
- Packet forwarding.
- Internetworking.
- Fragmentation support where required.
Distance Vector Routing
A router maintains information about destination distance and next hop. Routers normally exchange routing information with neighbours.
Problems may include:
- Slow convergence.
- Routing loops.
- Count-to-infinity behaviour in basic algorithms.
Link State Routing
A router learns its links, distributes link-state information, creates a topology database and calculates shortest paths.
Advantages include:
- Better network-topology knowledge.
- Generally faster convergence.
- More efficient path calculation in larger networks.
Conclusion
Distance Vector mainly learns routes through neighbouring routers, while Link State builds a broader map of the network.
9. Explain congestion, its causes, effects and control techniques.
Meaning
Network congestion occurs when the amount of traffic entering a network becomes greater than the available capacity of network resources.
Causes
- Sudden traffic bursts.
- Low-bandwidth links.
- Small router buffers.
- Slow packet-processing systems.
- Excessive retransmissions.
- Poor routing or traffic management.
Effects
- Long queueing delay.
- Packet loss.
- Retransmissions.
- Lower useful throughput.
- Poor user experience.
Control Techniques
- Traffic shaping.
- Admission control.
- Queue management.
- Feedback mechanisms.
- Rate reduction.
- TCP congestion-control mechanisms.
Flow Control vs Congestion Control
Flow control mainly protects the receiving system. Congestion control protects the entire network from excessive traffic.
Conclusion
Congestion control keeps network traffic within manageable limits and helps improve throughput and delay.
10. Explain IPv4 packet format and fragmentation.
IPv4 Datagram
An IPv4 datagram contains a header followed by the actual data payload.
Important Fields
- Version: Identifies IPv4.
- IHL: Header length.
- Total Length: Complete datagram size.
- Identification: Identifies fragments.
- Flags: Control fragmentation.
- Fragment Offset: Shows fragment position.
- TTL: Limits packet lifetime.
- Protocol: Identifies upper-layer protocol.
- Header Checksum: Detects header corruption.
- Source and Destination Address: Identify communicating hosts.
Fragmentation
If a datagram is larger than the MTU of a network link, IPv4 may divide it into smaller fragments where fragmentation is permitted.
Identification, Flags and Fragment Offset help manage the fragmented datagram.
Conclusion
The IPv4 header provides addressing, packet-lifetime control, protocol identification and fragmentation information needed for packet delivery.
11. Explain IPv4 addressing, subnetting and CIDR with an example.
IPv4 Address
An IPv4 address is 32 bits long and is written as four decimal numbers separated by dots.
Example: 192.168.10.25
Network and Host Portions
The prefix length or subnet mask determines which bits represent the network and which represent hosts.
Subnetting
Subnetting divides one large network into smaller logical networks.
Example
Consider:
192.168.10.0/24
If the network is divided using a /26 prefix, each subnet has 64 total addresses.
- 192.168.10.0/26
- 192.168.10.64/26
- 192.168.10.128/26
- 192.168.10.192/26
In traditional subnet calculations, each /26 provides 62 normal usable host addresses because the network and broadcast addresses are reserved.
CIDR
CIDR stands for Classless Inter-Domain Routing. It uses prefix lengths such as /24, /25 and /26 rather than depending only on fixed address classes.
Advantages
- More flexible IP allocation.
- Better utilisation of address space.
- Supports route aggregation.
- Allows networks to be sized according to actual requirement.
12. Explain IPv6 and compare IPv4 and IPv6.
Introduction
IPv6 is the newer version of the Internet Protocol developed primarily to provide a much larger address space and modernise IP communication.
IPv6 Address
IPv6 uses 128-bit addresses represented using hexadecimal groups.
Example: 2001:db8:85a3::8a2e:370:7334
Main Features
- 128-bit address space.
- Simplified base header.
- Extension-header support.
- Improved autoconfiguration support.
- No traditional IPv4-style broadcast.
- Better scalability for Internet growth.
| Feature | IPv4 | IPv6 |
|---|---|---|
| Address size | 32 bits | 128 bits |
| Notation | Dotted decimal | Hexadecimal |
| Address space | Smaller | Extremely large |
| Base header | More variable | Simplified fixed-size base header |
| Broadcast | Supported | Traditional broadcast not used |
Conclusion
IPv6 solves the address-space limitation of IPv4 and provides a more scalable foundation for continued Internet growth.
13. Explain Transport Layer functions and compare TCP and UDP.
Transport Layer
The Transport Layer provides logical process-to-process communication between applications running on different network hosts.
Main Functions
- Port addressing.
- Segmentation.
- Reassembly.
- Multiplexing and demultiplexing.
- Connection management.
- Flow control.
- Reliable delivery where supported.
TCP
TCP is connection-oriented and provides reliable, ordered byte-stream delivery. It uses acknowledgements, sequence numbers and retransmission.
UDP
UDP is connectionless and has lower overhead. It sends independent datagrams and does not provide TCP-style reliable ordered delivery.
| TCP | UDP |
|---|---|
| Connection-oriented | Connectionless |
| Reliable mechanisms | No built-in reliable delivery |
| Ordered byte stream | Datagram based |
| Higher overhead | Lower overhead |
Conclusion
TCP is used when reliability and ordering are important. UDP is useful when lower overhead, speed or application-controlled reliability is preferred.
14. Explain TCP connection establishment, termination and window management.
TCP Three-Way Handshake
TCP establishes a connection using a three-step exchange.
Step 1: SYN
The client sends a SYN segment to begin connection establishment.
Step 2: SYN-ACK
The server acknowledges the client's request and sends its own synchronization information.
Step 3: ACK
The client acknowledges the server response and the connection becomes established.
Connection Termination
Because TCP is full duplex, both directions are normally closed separately using FIN and ACK messages.
Window Management
TCP allows multiple bytes to remain in transit before acknowledgement.
Two important controls are:
- Receiver Window: Protects the receiver from buffer overflow.
- Congestion Window: Limits transmission according to network congestion.
Conclusion
TCP uses connection establishment, reliable sequence control and window management to provide dependable end-to-end communication.
15. Explain Session Layer, Presentation Layer, cryptography and Application Layer services.
Session Layer
The Session Layer establishes, manages and terminates communication sessions.
Main functions include:
- Dialogue control.
- Session management.
- Synchronization.
- Checkpointing.
Remote Procedure Call
RPC allows a program to invoke a procedure on another computer while making the request appear similar to a local procedure call.
Presentation Layer
The Presentation Layer deals with data representation and transformation.
Main functions include:
- Format translation.
- Character-code conversion.
- Compression.
- Representation changes.
Cryptography
Cryptography protects information using mathematical techniques.
- Symmetric encryption: Uses the same secret key.
- Asymmetric encryption: Uses public and private keys.
- Hashing: Produces a fixed-size one-way digest.
- Digital signature: Supports authenticity and integrity verification.
Application Layer
The Application Layer provides networking services to user applications.
Examples include:
- File transfer.
- Email.
- Web communication.
- Virtual-terminal access.
- Directory and naming services.
Conclusion
The upper OSI layers connect network communication with actual applications, manage communication sessions, transform data and support secure information exchange.
Computer Networks Final Practice Checklist
Before your semester exam, make sure you can answer these topics without opening your notes.
- Explain all seven OSI layers.
- Compare OSI and TCP/IP.
- Draw and compare network topologies.
- Explain guided and unguided media.
- Compare switching techniques.
- Explain MAC and ALOHA.
- Explain Data Link Layer functions.
- Compare Go-Back-N and Selective Repeat.
- Solve CRC and Hamming Code basics.
- Explain routing algorithms.
- Differentiate flow control and congestion control.
- Explain tunneling and fragmentation.
- Draw IPv4 packet format.
- Solve basic subnetting questions.
- Compare IPv4 and IPv6.
- Compare TCP and UDP.
- Draw TCP three-way handshake.
- Explain TCP window management.
- Explain Session Layer and RPC.
- Explain symmetric and asymmetric cryptography.
- Explain hashing and digital signatures.
- Explain Application Layer services.
- Explain how the Internet connects different networks.
Final Words
Computer Networks becomes easier when you stop reading the same notes again and start testing yourself. MCQs help you find small conceptual mistakes, short questions improve recall, and long questions show whether you can explain the complete topic properly.
Use this page as a practice resource instead of trying to memorise every answer word for word. First understand the concept, close the answer, and write it yourself. If you cannot explain a topic clearly, return to the related detailed chapter from the 37-chapter study map.
A strong Computer Networks preparation should include theory, comparisons, diagrams, protocol working and basic numerical practice. If these areas are clear, semester revision becomes much easier.
