What is a Hash Collision?

If you insert a new key into a hash map and the hash function returns the same bucket as an existing key, what will happen and how does the map handle it?

How would you implement a simple hash table that uses chaining to resolve collisions?

We saw a spike in lookup latency for our session cache and the logs show many keys ending up in the same bucket. How would you investigate and fix a possible hash‑collision issue?

When choosing between open addressing and separate chaining for a feature that stores up to 10 k items, what trade‑offs do you consider regarding collisions?

Our distributed key‑value store uses consistent hashing, but a poor hash function is causing many keys to map to the same node. What impact does that have on load balancing and how would you redesign the hashing strategy?

Design a collision‑resilient hashing layer for a high‑throughput logging system that must keep average insert time O(1) even under adversarial inputs.

We are migrating a legacy monolith that uses a custom hash for sharding data across multiple databases, and the current hash creates hot shards due to collisions. How would you lead a cross‑team redesign to improve distribution while minimizing disruption?

At a platform level, how would you evaluate and select a hash algorithm for a global CDN cache handling billions of requests per day, considering collision resistance, performance, and future scalability?