Site Reliability Engineer (L5) - Security Engineering

Netflix

Given a string containing digits from 2-9 inclusive, return all possible letter combinations that the number could represent. Return the answer in any order. A mapping of digit to letters (just like on the telephone buttons) is given below. Note that 1 does not map to any letters. 2: abc 3: def 4: ghi 5: jkl 6: mno 7: pqrs 8: tuv 9: wxyz Example 1: Input: digits = 23 Output: [ad,ae,af,bd,be,bf,cd,ce,cf] Example 2: Input: digits = Output: [] Example 3: Input: digits = 2 Output: [a,b,c]

Netflix

Let's say Netflix is experiencing slow streaming speeds for users in a specific geographic region. As a software engineer, how would you approach diagnosing and resolving this issue? Be specific and consider the following: Initial Assessment: What steps would you take to confirm the issue and gather initial data? Consider the metrics you'd want to examine, such as: Average buffering times Error rates during playback Network latency CPU/Memory utilization on streaming servers Possible Causes: Outline potential causes for the slow streaming speeds. Think about factors like: Network congestion in the region Issues with Netflix's content delivery network (CDN) servers in that region Problems with peering agreements with local ISPs Software bugs in the Netflix app or streaming infrastructure Unexpected spikes in user traffic Troubleshooting Steps: Describe the troubleshooting steps you would take to narrow down the cause. This could involve: Analyzing server logs for errors Running network diagnostics (e.g., traceroute, ping) to identify bottlenecks Testing different CDN servers in the region Checking the health of the origin servers Simulating user traffic to stress-test the system Resolution: How would you address the identified cause? This might include: Re-routing traffic to different CDN servers Increasing server capacity in the affected region Optimizing the streaming protocol or encoding settings Working with ISPs to improve network connectivity Deploying software fixes to address bugs Prevention: What measures can be taken to prevent similar issues from occurring in the future? Consider: Improving monitoring and alerting systems Implementing automated failover mechanisms Regularly stress-testing the infrastructure Diversifying CDN providers For example, if high network latency is detected, how would you investigate the path between Netflix's servers and the user's devices? What tools would you use, and what specific data points would you look for? Explain your reasoning behind each step and how it contributes to solving the problem. Detail the specific technologies and Netflix-specific knowledge you would need to effectively troubleshoot.

Netflix

Tell me about a time you went above and beyond what was expected of you.