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CS 432 - MCQs and Question and Answer
Modeling and Simulation (Virtual University of Pakistan)
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1. Size of scalar results file size is ________ vector results file.
Often greater than Often less than Often equal to Always equal to
2. Ability to grow is known as _________.
Scalability Availability Reliability Efficiency
4. In HTTP Response, which of the code is used for Bad Request?
404 301 505 400
5. It requires _______ RTTs per object in modeling non persistence connections.
1 2 3 4
7. During periods of congestion, _____queuing benefits UDP flows over TCP flows.
FCFS Priority LIFO FIFO
8. _________ windows fail to provide adequate control of packet delay.
Peer to peer Hop by hop Node to node End to end
9. Poisoned reverse does not work if more than ________ neighbors are involved in looping.
1 2 3 4
10. Intserv (QoS model) simulate the “virtual circuit” of ATM or frame relay on layer _____.
2 3 4 5
11. HSRP also works for proxy _______.
ARP Broadcast Any cast Multicast
12. ________ is a sequence of bits that delimits a frame’s Start and End.
Flag Index Ip Frame
13. Directed graph is represented with the help of _________.
G(N, E) E(G, N) N(E, G) E(N, G)
14. Receiver in each edge can decode the transmission from _______ node.
Head Tail Middle Random
15. IEEE 802.16 is an emerging ________ technology.
Wire line MAN Wireless WAN Wireless MAN Wireless VLAN
16. ________ layer incorporates error detection.
Session Transport Network Datalink
17. In TCP congestion control, Rate = Cong Win/ ________.
RTT Last Byte Sent Last Byte Recv
18. The _____ queuing system consists of a single queuing station with a single server.
M/M/1 M/N/! M/M/0 M/N/0
19. QoS routing is to find a _________ route for the session.
Good Shortest Delayed Typical
20. Weighted fair queue supports bit by bit ___________ scheduling.
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Round robin FIFO LIFO Priority Queue
21. Route lookup essentially involves tracing _______ bit destination address in the tries to find the
vertex.
16 32 64 128
22. ________ Queues provide best effort services.
Priority FIFO LIFO Fair
23. IN Max Frame Size computation Ethernet recommends _______ frame size as maximum.
1500 Bytes 1600 Bytes 100 Bytes 1700 Bytes
24. _______ identifies the operation in the wake of TimeOut.
NFC 2581 RFC 2581 SFC 2581 TFC 2581
25. _________ is the complexity of the link state protocol in datagram networks.
0 (n) 0 (log n) 0 (n log n) 0 (n2)
26. Every router on source- dest path maintains _______ for each passing connection.
State Flow Control Connection
27. In RFC 3439, average buffering equals to _________ RTT.
Same Typical Complex Different
28. In Parity Checks technique ________ parity detect single bet errors.
Single bit Multiple bits 0 bits Error bit
29. In which of the following technique, one checksum is computed over the header and another
checksum computed over entire packet.
TCP and UDP IP XTP TCP and IP
30. Packets in priority queue are scheduled in ___________ order.
LIFO FIFO Ascending Descending
31. Ethernet recommends minimum frame size up to _________.
64 Bits 32 Bits 156 MB 64 Bytes
32. Packet transmission in ALOHA protocol is _______.
Dependent Independent Synchronized Randomized
33. Broadband access technology is based on __________.
Shared medium and long distance
Non-shared medium and short distance
Shared medium and short distance
Non-shared medium and long distance
34. Ad hoc network has __________.
Fixed number of nodes Proper infrastructure No proper Non-spatial
infrastructure
35. Wireless LAN protocol stack does not include ______.
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Logical link control Radio Passive optical network 802.11 MAC
36. Degree of mobility in network where user moves between access network, while maintaining
ongoing connections is knowns as _________.
Moderate Mobility High Mobility Low Mobility No Mobility
37. WiMAX stand for worldwide interoperability for microwave access.
38. Mingwenv means Minimalist GNU for Windows Environment.
39. _________ file is used to hold OMNeT++ configuration and parameters of our model.
Omnet pp .ini Omnet++ .ini Omnet++ .cmd Omnetpp .ned
40. Total time for N objects in persistent connection is _______.
(N)*RTT + N* Transmit (N+1)*RTT + 2RTT + N*Transmit N*2RTT + N*Transmit
time N*transmit time time time
41. Leaky bucket is related to the buffering of the traffic. What does the term “leaky” mean?
In the context of the Leaky Bucket algorithm, "leaky" refers to the gradual release of excess packets
from the buffer, allowing a steady flow of traffic while preventing bursts and congestion. It's like a
bucket with a small hole, where water (packets) leaks out at a controlled rate, preventing overflow.
42. What is the concept of flooding? Give an example of its application?
Flooding is a networking concept where a packet is sent to every possible path or node in a network to
ensure it reaches its destination.
Example: In Ethernet networks, when a switch receives a packet with an unknown destination MAC
address, it floods the packet to all ports except the one it arrived on, to ensure it reaches its intended
destination.
Flooding can be used in various applications, including:
- Routing protocols
- Network discovery
- Multicast and broadcast transmissions
43. Enlist at least three service provided by DLL (Data Link Layer)?
1. Framing: The DLL breaks down data into frames, adding headers and trailers to ensure proper
synchronization and error detection.
2. Error Detection and Correction: The DLL detects errors in frames using techniques like CRC (Cyclic
Redundancy Check) and corrects them using protocols like ACK/NAK (Acknowledgment/Negative
Acknowledgment).
3. Flow Control: The DLL regulates the amount of data sent by the sender to prevent network
congestion, using protocols like Stop-and-Wait, Sliding Window, and Token Passing.
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44. Describe the Channel Behavior support in INET to Simulate Parity Scheme Failure?
In INET, Channel Behavior support simulates parity scheme failure by introducing errors into the
transmission channel. This is done by configuring error rates, such as:
- Bit Error Rate (BER)
- Packet Error Rate (PER)
- Burst Error Rate
These error rates randomly corrupt bits or packets, mimicking parity scheme failures like single-bit
errors, multiple-bit errors, or burst errors. This allows for testing and evaluation of error detection and
correction mechanisms in network protocols.
45. State the main difference between Random request mode and Scripted mode using HTTL browser in
OMNET++?
The main difference between Random Request Mode and Scripted Mode in OMNET++'s HTTP browser
is:
Random Request Mode:
- Generates requests randomly based on statistical distributions
- Simulates unpredictable user behavior
- Requests are generated on the fly
Scripted Mode:
- Executes a predefined script of requests
- Simulates specific, repeatable user behavior
- Requests are scripted in advance
In summary, Random Request Mode introduces variability, while Scripted Mode ensures reproducibility.
46. In today’s client-server architecture, caching is used to process the client requests. Write down any
two main advantages of using cache in client-server architecture?
Two main advantages of using cache in client-server architecture are:
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1. Reduced Latency: Cache stores frequently accessed data, allowing for faster retrieval and reduced
response time.
2. Improved Scalability: Cache reduces the load on servers by minimizing the number of requests,
enabling them to handle more clients and requests.
47. Fair Queue is foundation for scheduling disciplines. You are required to mentions its benefits.
The benefits of Fair Queue (FQ) scheduling discipline are:
1. Prevents Starvation: Ensures each flow gets a fair share of bandwidth, preventing any single flow from
dominating the network.
2. Reduces Congestion: Limits the amount of data sent by each flow, reducing network congestion and
improving overall performance.
3. Improves Fairness: Allocates bandwidth fairly among flows, ensuring each flow gets an equal
opportunity to transmit data.
48. “All routers are identical with a flat network”, is not true in practice, as routers are varied in different
feature. You are required to write such factors on which basis, router varies with each other?
Routers vary based on several factors, including:
1. Performance (speed, throughput)
2. Routing protocols (OSPF, EIGRP, BGP)
3. Network size (small, medium, large)
4. Security features (firewall, VPN, IDS/IPS)
5. Interface types (Ethernet, serial, wireless)
6. Operating System (proprietary, open-source)
7. Power and redundancy options
8. Management and monitoring capabilities
9. Quality of Service (QoS) features
10. Price and vendor (cost, brand, support)
These factors result in diverse routers, each suited for specific network needs.
49. IEEE 802.15.4 standard defines the operation of low rate wireless personal area networks
(LR WPANs). Enlist any five feature of IEEE 802.15.4 standard.
Certainly, here are the key points about the IEEE 802.15.4 standard.
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Low Data Rate: Designed for Low-Rate Wireless Personal Area Networks (LR WPNs) with modest
bandwidth requirements.
Low Power Consumption: Optimized for energy efficiency, extending battery life for battery-operated
devices.
Short Range Communication: Suited for short-range connections, covering distances of tens to a few
hundred meters.
Frequency Bands: Supports various frequency bands, including 2.4 GHz ISM and sub-GHz bands, offering
flexibility based on local regulations and interference concerns.
Network Topologies: Supports both star and peer-to-peer (mesh) network topologies, allowing
communication through central coordinators or directly between devices.
50. Enlist five factors which affect the efficiency of torrent.
Factors affecting efficiency
• Heterogeneous upload capacity
• Diversities of neighbor selecting mechanisms
• Geographical distribution of peers
• Downloading rates of LocalBT clients
• Peer selection policy
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