MCQs

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1. Which port is designated for FTP data transfer and is considered insecure due to lack of encryption?
   a. 20
   b. 22
   c. 23
   d. 25
   Answer: ascribd+1
2. Which port is used for FTP control and can be exploited using brute-force and directory traversal attacks?
   a. 20
   b. 21
   c. 22
   d. 25
   Answer: bnetwrix+1
3. Which port is commonly used for SSH but still suffers from brute-force and leaked key vulnerabilities?
   a. 21
   b. 22
   c. 23
   d. 25
   Answer: bnetwrix
4. What is the main security risk associated with Telnet on port 23?
   a. Encryption
   b. Eavesdropping
   c. Data integrity
   d. Authentication
   Answer: bnetwrix
5. Which port is primarily used for SMTP and known for susceptibility to spam and spoofing?
   a. 21
   b. 23
   c. 25
   d. 53
   Answer: cnetwrix
6. DNS operates mainly over which port, known for vulnerability to DDoS attacks?
   a. 25
   b. 53
   c. 80
   d. 110
   Answer: bnetwrix
7. EternalBlue exploited which port, leading to the WannaCry ransomware attack?
   a. 137
   b. 139
   c. 445
   d. 3389
   Answer: cnetwrix
8. Which port is associated with Telnet and is considered highly insecure and deprecated?
   a. 21
   b. 22
   c. 23
   d. 25
   Answer: cnetwrix
9. Port 80 is often targeted for which web-based attack due to lack of encryption?
   a. Brute-force
   b. Cross-site scripting
   c. Phishing
   d. Sniffing
   Answer: bnetwrix
10. Port 443 is generally secure, but what vulnerability may persist?
    a. Man-in-the-middle
    b. SQL injection
    c. Misconfigured SSL/TLS
    d. Flooding
    Answer: cnetwrix
11. NetBIOS over TCP/IP services use which ports that can leak NTLM hashes?
    a. 53 and 80
    b. 137 and 139
    c. 110 and 143
    d. 8080 and 8443
    Answer: bnetwrix
12. Server Message Block (SMB) service runs over which risky port, frequently targeted by malware?
    a. 20
    b. 21
    c. 445
    d. 3389
    Answer: cnetwrix
13. Which port is used for unsecured HTTP services and vulnerable to packet interception?
    a. 80
    b. 443
    c. 25
    d. 53
    Answer: anetwrix
14. Which port is used for secure Web services but can be compromised if SSL/TLS is outdated?
    a. 80
    b. 443
    c. 21
    d. 3389
    Answer: bnetwrix
15. Which alternative HTTP port is risky due to misconfigured applications?
    a. 110
    b. 8080
    c. 143
    d. 3389
    Answer: bnetwrix
16. Which port is used by Remote Desktop Protocol and is often brute-forced by attackers?
    a. 445
    b. 8080
    c. 1433
    d. 3389
    Answer: dnetwrix
17. SQL Server mainly uses which port for external connections, often exposed to malware distribution?
    a. 143
    b. 1433
    c. 3306
    d. 25
    Answer: bnetwrix
18. Port 3306 is the default for which common database, vulnerable to privilege escalation?
    a. MSSQL
    b. MySQL
    c. Oracle
    d. PostgreSQL
    Answer: bnetwrix
19. Which port is used by IMAP, vulnerable to packet sniffing if unencrypted?
    a. 25
    b. 110
    c. 143
    d. 995
    Answer: cnetwrix
20. Which port is known for unsecured POP3 service, often exploited for unauthorized access?
    a. 110
    b. 143
    c. 993
    d. 995
    Answer: anetwrix
21. SMTP open relay vulnerabilities occur on which port?
    a. 25
    b. 80
    c. 443
    d. 1433
    Answer: anetwrix
22. Which port is designated for HTTPS traffic and reliant on properly patched SSL?
    a. 443
    b. 80
    c. 993
    d. 25
    Answer: anetwrix
23. An unprotected database is commonly exposed via which port number for MSSQL?
    a. 3306
    b. 1433
    c. 139
    d. 3389
    Answer: bnetwrix
24. UDP-based DNS amplification attacks typically target which port?
    a. 80
    b. 53
    c. 21
    d. 443
    Answer: bnetwrix
25. Which port is commonly used by HTTPS proxy services and targeted in attacks on web applications?
    a. 443
    b. 8443
    c. 80
    d. 22
    Answer: bnetwrix
26. Which port is best described as “high-risk” for remote management, often targeted in brute-force attacks?
    a. 22
    b. 23
    c. 3389
    d. 445
    Answer: cnetwrix
27. Port 137 is used for which protocol and exposes machines to credential theft?
    a. FTP
    b. NetBIOS
    c. SMTP
    d. SSH
    Answer: bnetwrix
28. Which port should be closed if not used, as it’s often part of NetBIOS exploits?
    a. 443
    b. 137
    c. 3389
    d. 110
    Answer: bnetwrix
29. Which port is associated with outdated file transfer protocol service, risky for sensitive data?
    a. 21
    b. 22
    c. 23
    d. 25
    Answer: anetwrix
30. Which port number for POP3S provides secure mail retrieval?
    a. 993
    b. 995
    c. 110
    d. 143
    Answer: bnetwrix
31. Attackers may exploit SQL injection primarily through which web port?
    a. 80
    b. 443
    c. 1433
    d. 22
    Answer: anetwrix
32. DDoS attacks most commonly disrupt services operating on which port?
    a. 25
    b. 53
    c. 80
    d. 445
    Answer: cnetwrix
33. Which port is recommended for secure management instead of Telnet?
    a. 22
    b. 23
    c. 53
    d. 443
    Answer: anetwrix
34. MySQL, often targeted by attackers, defaults to which port?
    a. 3306
    b. 1433
    c. 23
    d. 110
    Answer: anetwrix
35. Which port exposes SNMP services and can lead to unauthorized system access?
    a. 161
    b. 25
    c. 110
    d. 3389
    Answer: anetwrix
36. Anonymous authentication is a risk on which port?
    a. 21
    b. 20
    c. 22
    d. 23
    Answer: anetwrix
37. IMAP over SSL is much less vulnerable on which port compared to plain IMAP?
    a. 443
    b. 993
    c. 995
    d. 143
    Answer: bnetwrix
38. Cross-site request forgery attacks can be launched via which port?
    a. 110
    b. 80
    c. 443
    d. 25
    Answer: bnetwrix
39. BlueKeep vulnerability targets which Microsoft RDP port?
    a. 3389
    b. 445
    c. 1433
    d. 137
    Answer: anetwrix
40. Directory traversal attacks are possible through which protocol’s assigned port?
    a. FTP (21)
    b. SMTP (25)
    c. Telnet (23)
    d. SSH (22)
    Answer: anetwrix
41. Which port is known for exposing machines to NTLM hash capture?
    a. 137
    b. 445
    c. 3389
    d. 143
    Answer: bnetwrix
42. Which port can be used for man-in-the-middle attacks due to no encryption?
    a. 23
    b. 80
    c. 443
    d. 8080
    Answer: anetwrix
43. Open port vulnerabilities expand the attack surface, especially when which port is left open without necessity?
    a. 3389
    b. 23
    c. 137
    d. 445
    Answer: anetwrix
44. SQL injection is a risk for services running on which port?
    a. 80
    b. 443
    c. 1433
    d. 3306
    Answer: anetwrix
45. Which port is known for unencrypted email communication, risking interception?
    a. 25
    b. 993
    c. 80
    d. 22
    Answer: anetwrix
46. SMB brute-forcing often occurs over which port?
    a. 445
    b. 21
    c. 3389
    d. 80
    Answer: anetwrix
47. Which port is targeted by attackers using SQL injection against poorly secured web applications?
    a. 80
    b. 443
    c. 8080
    d. 8443
    Answer: anetwrix
48. Unauthorized access to MySQL often occurs through which port?
    a. 3306
    b. 1433
    c. 23
    d. 80
    Answer: anetwrix
49. Which port should always be avoided for external access management due to high risk?
    a. 22
    b. 23
    c. 3389
    d. 445
    Answer: cnetwrix
50. Which port is designated for IMAP over SSL, making it less susceptible to interception?
    a. 993
    b. 995
    c. 110
    d. 143
    Answer: anetwrix

1. https://www.scribd.com/document/832878645/250-TOP-MCQs-on-Ports-and-Its-Types-and-Answers-2024
2. https://blog.netwrix.com/open-ports-vulnerability-list
3. https://www.sanfoundry.com/computer-networks-questions-answers-port/
4. https://www.watelectronics.com/mcq/computer-port/
5. https://reck.ac.in/wp-content/uploads/2023/04/DCN_MCQ-Ashwini-.pdf
6. https://testbook.com/objective-questions/mcq-on-two-port-networks–5eea6a0e39140f30f369e561
7. https://www.all-about-security.de/identifying-secure-and-unsecured-ports-and-how-to-secure-them/
8. https://www.speedguide.net/ports_sg.php
9. https://www.youtube.com/watch?v=sY3p93_FWqo
10. https://www.tenable.com/tenable-io-dashboards/vulnerabilities-by-common-ports-dashboard
11. https://www.interviewbit.com/computer-network-mcq/
12. https://www.geeksforgeeks.org/computer-networks/50-common-ports-you-should-know/
13. https://www.webasha.com/blog/most-commonly-used-tcp-and-udp-ports-list-with-services-for-ethical-hacking-networking-and-cybersecurity
14. https://www.scribd.com/document/866762937/MCQS-ON-COMPUTER-PORTS-51755470-2025-04-07-10-42
15. https://www.stationx.net/common-ports-cheat-sheet/
16. https://www.e2enetworks.com/blog/is-open-port-vulnerable
17. https://www.sanfoundry.com/cyber-security-questions-answers-experienced/
18. https://www.cobalt.io/blog/common-network-security-vulnerabilities
19. https://testbook.com/objective-questions/mcq-on-tcpudp-and-sockets-congestion-control–5eea6a0939140f30f369d8f9
20. https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers