Can You Ace These 35 IT Fundamentals Quiz Questions?

Part 1: Multiple Choice Questions

1. Which statement about virtual LAN (VLAN) is incorrect?

A. Users in different VLANs can communicate directly B. Each VLAN’s workstations can belong to different LANs C. A VLAN is a logical group of LAN subnets independent of physical location D. VLANs can flexibly control broadcast traffic

2. Which description of a system call is wrong?

A. The called routine runs in user mode B. System calls provide various OS services C. System calls forward application requests to the kernel D. System calls protect operations that must run in kernel mode

3. Which IP address can be assigned to a host?

A. 256.1.3.4 B. 197.3.11.0 C. 199.5.89 D. 11.15.33.235

4. A frog can jump 1 step, 2 steps … up to n steps at a time. How many different ways can it reach an n‑step staircase?

A. 2^(n‑1) B. 2·(n‑1) C. 2^n D. 2n

5. After evaluating the expression a = 5 ? 0 : 1, what is the final value of variable a?

A. 5 B. 1 C. 0 D. true

6. Assuming the numeral system is base‑n, the equality 567 × 456 = 150216 holds. What is n?

A. 9 B. 12 C. 13 D. 18

7. The network address is 172.16.0.0 with subnet mask 255.255.224.0. Which statement is correct?

A. One subnet’s broadcast address is 172.16.32.255 B. One subnet’s broadcast address is 172.16.128.255 C. The division creates 8 usable subnets D. The division creates 6 usable subnets

8. Before assigning an order to a driver, we need the probability that the driver accepts the order. Given two orders A and B with acceptance probabilities Pa and Pb respectively, what is the probability the driver chooses order A when both are offered simultaneously?

A. Pa B. Pa·(1‑Pb) C. Pa·(1‑Pb) / (1‑Pa·Pb) D. [1‑(1‑Pa)(1‑Pb)]·Pa / (Pa+Pb)

9. In a TCP connection, which state cannot appear on the side that actively closes the connection?

A. CLOSE_WAIT B. FIN_WAIT2 C. TIME_WAIT D. FIN_WAIT1

10. Which statement about TCP and UDP is correct?

A. Both are connection‑less B. TCP is connection‑less, UDP is connection‑oriented C. TCP suits unreliable WANs, UDP suits reliable LANs D. TCP suits reliable LANs, UDP suits unreliable WANs

11. In a GCC environment, given int arr[5] = {1,2,3,4,5};, what is the result of *(*(&arr+1)-1)?

A. 1 B. 0 C. 4 D. 5

12. In the figure (six squares a‑g, a has side length n), what is the area of the red region?

A. 65·n² B. 75·n² C. 80·n² D. 85·n²

13. A frog can jump any number of steps from 1 to n each time. How many ways can it reach an n‑step staircase (n>0)?

A. 2^(n‑1) B. 2·(n‑1) C. 2^n D. 2n

14. The following code runs into an error; which line is most likely responsible?

A. 1 B. 2 C. 3 D. 4

15. If a binary tree’s preorder traversal is abcdefg and inorder traversal is bcedagf, what is its postorder traversal?

A. edbcgfa B. edcbfga C. edcbgfa D. ecdbgfa

16. In Linux, a file has permission string -rw‑‑wx‑‑x. What is its numeric (octal) representation?

A. 641 B. 742 C. 652 D. 651

17. Which of the following groups consists of network‑layer protocols?

A. IP, TCP, UDP B. ARP, IP, UDP C. FTP, SMTP, Telnet D. ICMP, ARP, IP

18. Five elements A‑E are pushed onto a stack in order. During the push process, elements may be popped. How many possible pop sequences exist?

A. 41 B. 42 C. 43 D. 44

19. How many times does the loop in the following code execute?

A. 10 B. 11 C. 12 D. 20

20. What is the output of the following program?

A. 6.25 B. 6 C. 24 D. 25

21. Given the structure shown (see image), what is sizeof(struct B) on a 64‑bit system?

A. 24 B. 32 C. 40 D. 20

22. How many processes are created after the following code runs?

A. 10 B. 100 C. 1024 D. 2048

23. Which description of a system call is incorrect? (Same options as question 2)

A. The called routine runs in user mode B. System calls provide various OS services C. System calls forward requests to the kernel D. System calls protect kernel‑only instructions

24. Which action can translate a logical address into a physical memory address?

A. Compilation B. Relocation C. Linking D. Execution

25. Among the four necessary conditions for deadlock, which one is unrealistic to break?

A. Mutual exclusion B. No preemption C. Hold and wait D. Circular wait

26. The frequencies of characters a‑h are a:1, b:1, c:2, d:3, e:5, f:8, g:13, h:21. Using Huffman coding, what string does the bit sequence 110111100111010 represent?

A. fdheg B. ecgdf C. dchfg D. fehdg

27. What is the space complexity of the algorithm shown in the figure?

A. O(1) B. O(n) C. O(n!) D. O(n²)

28. What is the postfix expression of a‑b*(c‑d)/e+f?

A. abcd‑*e/‑f+ B. abcde‑*/‑f+ C. abcde*‑/‑f+ D. abcd*‑e/‑f+

29. There are 256 bottles, one is poisonous. With only a 2‑hour test window and results appearing after 2 hours, what is the minimum number of mice needed to identify the poisonous bottle?

A. 7 B. 8 C. 9 D. 255

Reference Answers:

1‑5: A A D A C

6‑10: D D D A C

11‑15: D D A B C

16‑20: D D B A C

21‑25: B D A B A

26‑29: A B A B

Part 2: Essay Questions

30. Explain the working principle of traceroute .

Reference answer: traceroute sends UDP packets with gradually increasing TTL values. When a router discards a packet because TTL reaches zero, it returns an ICMP “time exceeded” message, revealing that router. When the destination host receives a packet with an unreachable port, it returns an ICMP “port unreachable” message, indicating the final hop. The sequence of replies maps the path.

31. When you type a URL such as http://www.didichuxing.com into a browser and press Enter, describe the complete technical process, covering browser behavior, DNS resolution, TCP handshake, HTTP request/response, and rendering.

Reference answer: 1) DNS resolution – the browser checks its cache, then the OS cache, the router’s DNS, ISP DNS, and finally root DNS servers to obtain the IP address. 2) A TCP connection is established to the server’s IP using a three‑way handshake (SYN, SYN‑ACK, ACK). 3) The browser sends an HTTP GET request (including Host, User‑Agent, Connection, Cookie headers, etc.). 4) The server responds with HTTP status, headers, and the page content, which the browser renders.

32. Using the identifier a, give definitions for the following eight C declarations:

1) an integer variable 2) a pointer to an integer 3) a pointer to a pointer to an integer 4) an array of ten integers 5) an array of ten pointers to integers 6) a pointer to an array of ten integers 7) a pointer to a function that takes an int and returns an int 8) a pointer to a function that takes an int and returns an int

Reference answer:

int a;

int *a;

int **a;

int a[10];

int *a[10];

int (*a)[10];

int (*a)(int);

int (*a)(int);

33. Summarize the DNS lookup process for the domain www.didichuxing.com.

Reference answer: 1) The OS first checks the local hosts file. 2) If not found, it checks the local DNS resolver cache. 3) It queries the configured recursive DNS server; if the name is within the server’s authoritative zones, it returns the answer. 4) If the server has a cached answer, it returns it (non‑authoritative). 5) Otherwise the server follows the hierarchy: root servers → TLD (.com) servers → authoritative servers for the domain, possibly traversing additional delegations, until the IP address is obtained. 6) If the recursive server uses forwarding, it forwards the query to an upstream server, which repeats the process.

34. Design a data structure that can store any number in the range 0 ~ 2³² using 4 GB of memory, supporting insertion and deletion of arbitrary numbers. Provide the design idea and code.

Reference answer: (code image omitted for brevity)

35. List common server models, indicate which you have used, and briefly describe how you used them.

Reference answer: synchronous blocking, multi‑process, multi‑thread, select + multi‑thread, epoll + multi‑thread, epoll + thread pool.