SSC CGL Computer – Mock Test M3 – Computer Knowledge Module

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SSC CGL Computer – Mock Test M3 – Computer Knowledge Module – 20 questions, subject: Computer Knowledge. Every question has the correct answer with a one-line explanation; tap "Show Answer". Free practice for TNPSC, UPSC, SSC, Bank and RRB exams – Shanmugam IAS Academy, Coimbatore.

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1.  
The Mosaic browser, which helped make the Web popular, was released by NCSA in:

Correct Answer: B [1993]

Explanation:

Web proposal 1989 → first browser 1990 → Mosaic 1993 → public Internet in India 1995.

2.  
VSNL opened public Internet service in India on:

Correct Answer: D [15 August 1995]

Explanation:

Public dial-up Internet was launched by VSNL on 15 August 1995.

3.  
On which default port does an FTP client open its control connection?

Correct Answer: A [21]

Explanation:

FTP control 21, data 20; 22 is SSH; 25 is SMTP.

4.  
Statement-basedWhich is/are correct?
I. POP3 usually downloads mail to one device and removes it from the server.
II. SMTP is the protocol a mail app uses to download messages from the server.

Correct Answer: C [Only I]

Explanation:

SMTP sends mail; POP3 or IMAP fetch it.

5.  
Which Google search finds pages about 'budget' that do NOT mention 'railway'?

Correct Answer: D [budget -railway]

Explanation:

A minus sign before a word excludes it.

6.  
An e-mail is sent to 3 people in To, 2 in Cc and 4 in Bcc. How many recipient addresses can a person in the To line see?

Correct Answer: B [5]

Explanation:

To and Cc addresses are visible to all (3 + 2 = 5); Bcc addresses are hidden.

7.  
Which of these is a correctly formed IFSC?

Correct Answer: A [SBIN0001234]

Explanation:

11 characters: 4 letters for the bank, 0 as the 5th character, 6 characters for the branch.

8.  
On a cheque the MICR code is 600002017. Which part is the city code?

Correct Answer: C [600]

Explanation:

MICR = 3 digits city + 3 digits bank + 3 digits branch.

9.  
Only one of these card numbers passes the Luhn check-digit test. Which one?

Correct Answer: B [4532 0151 1283 0366]

Explanation:

Double every second digit from the right (subtract 9 if over 9), add all digits: only this number gives a multiple of 10.

10.  
From which date has RTGS been available 24x7x365?

Correct Answer: D [14 December 2020]

Explanation:

RTGS round the clock from 14 December 2020; NEFT 24x7 came earlier, on 16 December 2019.

11.  
Six computers are joined in a full mesh. Counting every computer, how many network ports are used for the mesh links altogether?

Correct Answer: D [30]

Explanation:

Each computer needs n − 1 = 5 ports: 6 × 5 = 30 (each of the 15 cables uses 2 ports).

12.  
A LAN uses the subnet mask 255.255.254.0. How many devices can get an address on it?

Correct Answer: A [510]

Explanation:

254.0 = 11111110.00000000 leaves 9 host bits; 2⁹ − 2 = 510 (network and broadcast addresses are reserved).

13.  
Under the old classful scheme, the address 10.45.3.2 belongs to which class?

Correct Answer: C [Class A]

Explanation:

First octet 10 lies in 1–126 → Class A (it is also in the private range 10.0.0.0/8).

14.  
Match the followingMatch the device with the highest OSI layer it works at:
P. Router Q. Hub R. Switch S. Gateway
1. Physical layer 2. Data Link layer 3. Network layer 4. Up to the Application layer

Correct Answer: B [P-3, Q-1, R-2, S-4]

Explanation:

Hub L1, switch L2, router L3, gateway up to L7.

15.  
What is the unit of data at the Transport layer of the OSI model called?

Correct Answer: B [Segment]

Explanation:

Bit (L1), frame (L2), packet (L3), segment (L4).

16.  
A hacker breaks into a company's system without permission but then reports the weakness instead of misusing it. Such a hacker is usually called a:

Correct Answer: C [Grey hat]

Explanation:

White hat works with permission; black hat is criminal; grey hat acts without permission.

17.  
Which of these is a one-way hash function rather than an encryption method?

Correct Answer: D [SHA-256]

Explanation:

SHA-256 gives a fixed-length hash that cannot be reversed; AES and DES are symmetric ciphers; RSA is public-key encryption.

18.  
A code is made of 5 capital letters (A–Z), and letters may repeat. How many different codes are possible?

Correct Answer: A [1,18,81,376]

Explanation:

26 choices for each of 5 places: 26⁵ = 1,18,81,376.

19.  
In symmetric encryption such as AES, how many keys are used to lock and unlock a message?

Correct Answer: D [One shared secret key]

Explanation:

Symmetric = one shared key for both steps; asymmetric (RSA) uses a public/private pair.

20.  
Assertion–Reason
A: A padlock in the address bar proves that the website is genuine and honest.
R: The HTTPS padlock shows that the connection to the site is encrypted.

Correct Answer: C [A is false but R is true]

Explanation:

R is true but A is false – a fraud site can also have HTTPS.

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📘 SSC CGL 2026 – Computer Knowledge (Tier II Paper I – Section III)
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