Security Program Manager, DC Security

Amazon

Write a program that prints the numbers from 1 to 100. But for multiples of three print “Fizz” instead of the number and for the multiples of five print “Buzz”. For numbers which are multiples of both three and five print “FizzBuzz”. Details: Your solution should be runnable and demonstrate the output. Focus on clean, readable code. Consider edge cases and error handling (though not strictly required for this basic version). Provide a brief explanation of your approach and any assumptions you made. Example: 1 2 Fizz 4 Buzz Fizz 7 8 Fizz Buzz 11 Fizz 13 14 FizzBuzz ... Variations (optional, for a more challenging exercise): Allow the user to input the upper limit of the range (instead of always going to 100). Allow the user to input the numbers to use for Fizz and Buzz (instead of always using 3 and 5). Allow the user to input the words to use for Fizz and Buzz (instead of always using Fizz and Buzz). Handle invalid inputs gracefully. This question assesses a candidate's basic programming skills, understanding of loops and conditional statements, and ability to write clean, understandable code. The variations allow for exploring error handling, input validation, and more flexible program design.

Amazon

Let's delve into the fascinating world of operating systems. Imagine you're designing a new OS, and you need to implement a memory management system. Discuss the following: Virtual Memory: Explain the concept of virtual memory. How does it help in managing memory efficiently, especially when dealing with processes that require more memory than physically available? Provide a specific example of a scenario where virtual memory shines, such as running multiple large applications concurrently on a system with limited RAM. What are the benefits and drawbacks of using virtual memory? Specifically discuss the performance overhead associated with page faults. Page Replacement Algorithms: Describe different page replacement algorithms (e.g., FIFO, LRU, Optimal). For each algorithm, provide a step-by-step example using a reference string of page accesses (e.g., 1, 2, 3, 4, 1, 2, 5, 1, 2, 3). Calculate the number of page faults for each algorithm. Discuss the trade-offs between the complexity of the algorithm and its performance in terms of minimizing page faults. Explain a situation where FIFO would perform worse than LRU, and vice versa. Memory Fragmentation: Explain internal and external fragmentation. Give examples for each. What are the causes of each type of fragmentation? What strategies can be used to mitigate memory fragmentation (e.g., compaction, paging, segmentation)? Discuss the advantages and disadvantages of each strategy. Protection and Security: How does the OS protect memory from unauthorized access by different processes? Explain the role of memory protection mechanisms like base and limit registers, and page table entries (PTEs) with protection bits. Describe a scenario where a process attempts to access memory outside of its allocated region, and explain how the OS would handle this situation to prevent security breaches. How can techniques like Address Space Layout Randomization (ASLR) further enhance memory security?

Amazon

Describe a time when a plan did not go as expected.