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Thursday 21 January 2021

CS8591 COMPUTER NETWORKS UNIT I MCQ


UNIT I INTRODUCTION AND PHYSICAL LAYER                                           

Networks – Network Types – Protocol Layering – TCP/IP Protocol suite – OSI Model – Physical Layer: Performance – Transmission media – Switching – Circuit-switched Networks – Packet Switching

 

1. Exchange of data between two devices via some form of transmission medium such as a wire cable.

A.    Data Communication          

B.    Network

Answer: A Data Communication

 

2. Information to be communicated which consist of text, numbers, pictures, sound or video combination.

A.    Sender

B.    Receiver

C.    Message

Answer: C Message

 

3. Elapsed time between an inquiry and a response

A.    Transit time

B.    Response time

Answer: B Response Time

 

4. Provides a dedicated link between two devices

A.    point-to-point connection

B.    multipoint connection

Answer: A point-to-point connection

 

 

5. In bus topology, a ________________is a connection running between the device and the main cable.

A.    Drop line

B.    tap

Answer: A Drop line

 

6. The physical layer is concerned with ___________

A.    bit-by-bit delivery

B.    process to process delivery

C.    application to application delivery

D.    port to port delivery

Answer: A bit-by-bit delivery

 

7. The physical layer translates logical communication requests from the ______ into hardware specific operations.

A.    network layer

B.    trasnport layer

C.    application layer

D.    data link layer

Answer: D data link layer

 

8. Each upper level protocol is supported by the services provided by one or more lower level protocols.

A.     hierarchical

B.    Root structure

Answer: A hierarchical

 

 

9. In TCP/IP, The duty of the application, transport, and network layers is

A.    hop-to-hop

B.    end-to-end

Answer: B  end-to-end

 

 

10. In TCP/IP, The duty of the data-link and physical layers is

A.    hop-to-hop

B.    end-to-end

Answer: A  hop-to-hop

 

 

11. In TCP/IP , in the bottom two layers, the packet created by the host is changed only by

A.    routers

B.    link-layer switches

Answer: A  routers

 

 

12. Responsible for taking the datagram and moving it across the link

A.    Data-link Layer

B.    Physical Layer

Answer: A  Data-link Layer

 

 

13. Responsible for creating a connection between the source computer and the destination computer.

A.    Data-link Layer

B.    Physical Layer

C.    Network layer

Answer: C Network layer

 

 

14. A protocol can decapsulate and deliver a packet to several next-higher layer protocols (one at a time).

A.    Multiplexing

B.    Demultiplexing

Answer: B Demultiplexing

 

 

15. A protocol at a layer can encapsulate a packet from several next-higher layer protocols (one at a time);

A.    Multiplexing

B.    Demultiplexing

Answer: A Multiplexing

 

 

16. It is a system in which a set of protocols that allows any two different systems to communicate regardless of their underlying architecture.

A.    Open System

B.    Closed System

Answer: A Open System

 

 

17. Four approaches that indicate network Performance

A.    Bandwidth

B.    Throughput

C.    Latency (delay)

D.    Jitter

E.     All the above

Answer: E  All the above

 

18. IS a measure of the number of bits that can pass through a network per second.

A.    Throughput

B.    Latency

Answer: A Throughput

 

19. Refers to the variation in the packet arrival time, that is an uneven delay in the delivery of audio or video packets.

Throughput

Latency

Jitter

Answer: C Jitter

 

20. Is the Physical path between source and destination that carry the information signals.

A.    Transmission media

B.    Transmission wavelength

Answer: A  Transmission media

 

 

21. Is a cable that accepts and transports signals in the form of light.

A.    Optical fiber

B.    twisted-pair cable

Answer: A Optical fiber

 

 

22. Coaxial cables are categorized by their

A.    Registered jack RJ ratings

B.    Radio Government (RG) ratings

Answer: B  Radio Government (RG) ratings

 

 

23. If the angle of incidence is ______to the critical angle, the light bends along the interface.

less than

equal

greater than

Answer: B equal

 

 

24. In this ______propagation, radio waves travel through the lowest portion of the atmosphere, hugging the earth.

A.    sky

B.    ground

C.    line-of-sight

Answer: B ground

 

 

25. In _________ propagation, very high-frequency signals are transmitted in straight lines directly from antenna to antenna

A.    sky

B.    ground

C.    line-of-sight

Answer: C line of sight

 

 

26. In _________ propagation, higher-frequency radio waves radiate upward into the ionosphere (the layer of atmosphere where particles exist as ions) where they are reflected back to earth.

A.    sky

B.    ground

C.    line-of-sight

Answer: A sky

 

27. Radio waves travel in all directions from the source, so that the transmitter and receiver do not have to be carefully aligned physically

A.    Uni directional

B.    Omni directional

Answer: B Omni directional

 

 

28. When an antenna transmits microwaves, the sending and receiving antennas need to be aligned since microwaves are

A.    Uni directional

B.    Omni directional

Answer: A Uni directional

 

 

29. Signals can be used for short-range communication in a closed area using line-of-sight propagation

A.    Infrared

B.    Microwaves

C.    Radiowaves

Answer: A Infrared

 

 

30. End to End circuit must be established in this phase

A.    Setup phase

B.    Data transfer phase

C.    Tear down phase

Answer: A setup phase

 

31. When a frame arrives at a switch, it has a VCI; when it leaves, it has a different VCI.

A.    True

B.    False

Answer: A true 

Thursday 7 January 2021

CP5291 SECURITY PRACTICES

 

CP5291 SECURITY PRACTICES

1. Define security services.

Security services is defined as a service that enhances the security of the data processing systems and the information transfers of an organization.

 

2. What is meant by zero day attack?

A zero-day attack or threat is an attack that exploits a previously unknown vulnerability in a computer application, meaning that the attack occurs on “day zero” of awareness of the vulnerability. This means that the developers have had zero days to address and patch the vulnerability.

0day exploits (actual software that uses a security hole to carry out an attack) are used or shared by attackers before the developer of the target software knows about the vulnerability.

 

3. What are the four phases of unknown vulnerability management process?

The unknown vulnerability management process consists of four phases:

  • Analyze: This phase focuses on attack surface analysis.
  • Test: This phase focuses on fuzz testing the identified attack vectors.
  • Report: This phase focuses on reproduction of the found issues to developers.
  • Mitigate: This phase looks at the protective measures.

 

4. Write a difference between sustained capture speed and peak capture speed.

The sustained captured speed is the rate at which a packet capture appliance can capture and record packets without interruption or error over a long period of time. This is different from the peak capture rate, which is the highest speed at which a packet capture appliance can capture and record packets. The peak capture speed can only be maintained for a short period of time, until the appliance’s buffers fill up and it starts losing packets.

 

5. Write the advantages of UTM.

UTM systems are multilayered and incorporate several security technologies into a single platform, often in the form of a plug-in appliance. UTM products can provide such diverse capabilities as antivirus, VPN, firewall services, and antispam as well as intrusion prevention.

Advantages:

  • Ease of operation and configuration.
  • Security features can be quickly updated to meet rapidly evolving threats.


6. Differentiate between hacker and cracker.

Hacker is a person who is extremely interested in exploring the things and recondite workings of any computer system or networking system. Hackers are expert programmers. These are also called Ethical Hackers or white hat hackers. The technique they use is called ethical hacking.

Crackers or Black Hat hackers are also called cheaters or simply criminals. They are called criminals because they intend to cause harm to security, stealing very useful data and using it in wrong ways. Phishers, who steal account information and credit card numbers, also fall into this category

 

7. What is trapdoor?

It is also called Backdoors, are pieces of code written into applications or OS to grant programmers access to programs without requiring them to go through the normal methods of access authentication.

 

8. List the four phases of Remus.

1. Checkpoint the changed memory state at the primary, and continue to the next epoch of network and disk request streams.

2. Replicate system state on the backup.

3. Send checkpoint acknowledgment from the backup when complete memory checkpoint and corresponding disk requests have been received.

4. Release outbound network packets queued during the previous epoch upon receiving the acknowledgment.

 

9. Write about XACML.

XACML  stands for eXtensible Access Control Markup Language . It is an open standard XML-based language designed to express security policies and access rights to information for Web services, digital rights management (DRM), and enterprise security applications.

 

10. Define Token and its types.

A token is a device that employs an encrypted key. There are both software and hardware tokens. The software tokens can be installed on a user’s desktop system, in the cellular phone, or on the smart phone. The hardware tokens come in a variety of form factors, some with a single button that both turns the token on and displays its internally generated passcode. Tokens operate in one of three ways:

  • time synchronous,
  • event synchronous, or
  • challenge-response (alsoknown as asynchronous

11. Define Man-in-the-middle attack.                      

The man-in-the-middle attack is one of the classical attacks that can be executed in a WSN environment. In this type of attack, the attacker intrudes into the network and attempts to establish an independent connection between a set of nodes and the sink node. He can be in either a passive or an active state. In a passive state, he simply relays every message among the nodes with the intention of performing an eavesdropping attack. In an active state, he can tamper with the intercepted data in an effort to break authentication     .          

 

12. What are the two attacks on WSN?       

In general, attacks can be divided into active and passive attacks:

Active Attack

In this type of attack, the attacker actively participates in all forms of communication (control and data) and may modify, delete, reorder, and replay messages or even send spoofed illicit messages to nodes in the network. Some other active attacks include node capturing, tampering with routing information, and resource exhaustion attacks.

Passive Attack

In this type of attack, the attacker is able to intercept and monitor data between communicating nodes, but does not tamper or modify packets for fear of raising suspicion of malicious activity among the nodes.

 

13. Write about Signature algorithms in LAN security.

Signature analysis is based on the following algorithms:

  • Pattern matching
  • Stateful pattern matching
  • Protocol decode-based analysis
  • Heuristic-based analysis
  • Anomaly-based analysis

                       

 

14. Write a difference between single mode vs. multimode.                                                          

Specification

Single mode fiber

Multimode fiber

Definition

Single-mode fiber has a narrow core, allowing only a single mode of light to propagate within the core

Multimode has a wide core and allows multiple modes of light to propagate

Outside diameter

125 microns

125 microns

Core size

core size between 8 and 10 micorns

core size between 62.5 μm OM1 and 50 μm OM2.

Cost of fiber

Less Expensive

Expensive

Transmission wavelengths

1260 nm to 1640 nm

850 nm to 1300 nm

Advantages/disadvantages

Provides higher performance, but building the network is expensive.

The fiber is more costly, but the network deployment is relatively inexpensive.

 

 

15. Give diagrammatic representations for deployment architecture of optical wireless security.       

                     Mesh                            Ring                            Point to Point  


16. Write about IR plan

An Incident Response (IR) Plan is a detailed set of processes and procedures that anticipate, detect, and mitigate the impact of an unexpected event that might compromise information resources and assets. It consists of six major phases.

  1. Preparation: Planning and readying in the event of a security incident.
  2. Identification. To identify a set of events that have some negative impact on the business and can be considered a security incident.
  3. Containment: During this phase the security incident has been identified and action is required to mitigate its potential damage.
  4. Eradication: After it’s contained, the incident must be eradicated and studied to make sure it has been thoroughly removed from the system.
  5. Recovery: Bringing the business and assets involved in the security incident back to normal operations.
  6. Lessons learned: A thorough review of how the incident occurred and the actions taken to respond to it where the lessons learned get applied to future incidents.

 

17. Write  the three Access control models.

Three main access control models are in use today: RBAC, DAC, and MAC

Role-Based Access Control (RBAC)

Discretionary Access Control (DAC)

Mandatory Access Control (MAC)

 

18. Write about Network based Intrusion detection system.

Network-based intrusion detection systems (NIDS) have been the workhorse of information security technology(figure). NIDS function in one of three modes:

  • Signature detection
  • Anomaly detection, and
  • Hybrid

 

19. What are the four types of evidence in Cyber Forensics In The Court System?

There are four types of evidence

1.      Documentary evidence

2.      Real evidence

3.      Witness testimony

4.      Demonstrative evidence

 

20. Write about Data Retention policies.

This leads us directly into data retention policies, A rigorous data retention policy will  prevent the exposure of outdated and irrelevant files. Deleted files are a security concern because they may still be extant. The following items present deleted data security challenges:

1. Email databases.

2. SQL log files.

3. Decommissioned servers.

4. Old backup tapes.

5. Forgotten share locations

 

21. Define Cyberforensics.

Cyber forensics is the acquisition, preservation, and analysis of electronically stored information (ESI) in such a way that ensures its admissibility for use as either evidence, exhibits, or demonstratives in a court of law.

 

22. Write about Plaintiffs and defendants.

When someone, an individual or an organization, decides it has a claim of money or damages against another individual or entity, they file a claim in court. The group filing the claim is the plaintiff, the other parties are the defendants.

 

23. Define P3P policy.

P3P (Platform for Privacy Preferences Project) allows Web sites to declare their privacy ractices in a standard and machine-readable XML format known as P3P policy. A P3P policy contains the specification of the data it protects, the data recipients allowed to access the private data, consequences of data release, purposes of data collection, data retention policy, and dispute resolution mechanisms.

 

24. Mention the advantages of Tor over AN.ON

Advantages of Tor over AN.ON are as follows:

1. Tor provides forward secrecy.

2. It is easy to set up new onion routers (“mixes”), which are run by many volunteers all over the world.

3. There are lower performance requirements for each “mix.”

4. Each mix is a possible bottleneck, however, in Tor, “mixes” that do not perform can be excluded from the dynamic routing.

 

25. Define onion routing. What are three phases in which onion routing protocol works?

Onion routing is intended to provide real-time bidirectional anonymous connections that are resistant to both eavesdropping and traffic analysis in a way that is transparent to applications.

The onion router infrastructure, the onion routing protocol works in three phases:

  • Anonymous connection setup
  • Communication through the anonymous connection
  • Anonymous connection destruction