NCERT Solutions for Class 9th Computer Science: Chapter 6 Security threats and Safety Measures
A. Multiple Choice Questions:
1. Which of the following is an anti-virus program
(b) Quick heal
(d) All of these
► (d) All of these
2. All of the following are examples of real security and privacy threats except:
► (a) Hackers
3. Trojan horses are very similar to virus in the matter that they are computer programs that replicate copies of themselves.
► (b) False
4._____________ monitors user activity on internet and transmit that information in the background to someone else.
(d) None of these
► (c) Spyware
5. Viruses are__________.
(a) Man made
(b) Naturally occur
(c) Machine made
(d) All of the above
► (a) Man made
6. Firewall is a type of ____________.
(c) Security threat
(d) None of the above
►(d) None of the above
7. Unsolicited commercial email is knownas ____________.
► (a) Spam
B. Match the following
|(1)||Virus||(a)||“Get Rich Quick” Scheme|
|(2)||Worm||(b)||Cool Web Search|
|(3)||Trojan Horse||(c)||I Love You|
|(3)||Trojan Horse||(c)||I Love You|
|(4)||Spyware||(d)||Cool Web Search|
|(5)||Spam||(e)||“Get Rich Quick” Scheme|
C. Answer the following questions:
1. While working on the computer, you notice that the system is working very slowly, files are corrupted, default home page on the web browser has changed, lot memory is consumed, and unnecessary pop-ups are coming. What can be the probable reason?
The computer gets infected from Spyware. It monitors user activity on the Internet and transmits that
information in the background to someone else. Spyware can also gather information about e-mail addresses and even passwords and credit card numbers. It also sends information back to the spy ware’s home base via the user’s Internet connection, thus it eats user’s internet bandwidth.
2. You have very important data on your computer. How will you ensure that this data remainssafe?
We can make our important data safe on computer through below steps:
1. Using Security software such as Norton antivirus, Symantec etc.
2. Beware of email attachments form unknown sources
3. Do not randomly download material from websites which has not been checked for security.
3. Never propagate hoax or chain emails.
4. Frequently back up important data and files.
5. Use encryption or sites that use encrypted data.
3. Differentiate between virus, worms and Trojan horses.
Virus- A computer virus is a program usually hidden within another simple program. It produces copies of itself and inserts them into other programs or files, in turn destroying the data and performing other malicious actions. Computer viruses are never naturally occurring; they are always man-made.
Worms- Worms are very similar to viruses in the manner that they are computer programs that
replicate copies of themselves (usually to other computer systems via network connections). Unlike viruses, worms exist as separate entities; they do not attach themselves to other files or programs.
Torjan Horses- A Trojan horse is a program that claims to rid your computer of viruses but instead
introduces viruses into the system. The Trojan program does not attach itself to the files like a virus nor replicate itself like a worm but it does provide unauthorized access to user’s computer. They are mostly spread through internet downloads and online gaming programs. They mostly affect the targeted computers.
4. How is a hacker different from a cracker?
Hackers are gifted programmers who gain access to the systems or network to show case the security loopholes to the administrators.
Cracker is an activist who had intentions of doing malicious activities. Crackers have an end goal of destroying data and network for personal monetary gains.