Design a system that can handle leading traffic for a social media platform's notifications system. Describe the key components you would include to ensure both scalability and reliability.

LeetCode #208 - Implement Trie (Prefix Tree) \nGiven a list of words, implement a trie with insert, search, and startsWith methods. Your implementation should support insert and search queries efficiently. \n### Method Signatures: \n```python \ndef insert(self, word: str) -> None: \n pass \ndef search(self, word: str) -> bool: \n pass \ndef startsWith(self, prefix: str) -> bool: \n pass \n``` \n### Input/Output: \nInput: ['apple', 'app'], search('app') -> true \nInput: ['apple', 'app'], startsWith('ap') -> true \n### Constraints: \n- All input words are lowercase alphabets. \n- Insert, search, and startsWith operations should be efficient (preferably O(M) where M is the length of the word). \n

Describe a challenging technical problem you faced in a previous role, how you approached it, and what the outcome was.