Full Stack developer interview questions

Force-pushing rewritten commits changes SHAs that teammates and CI already pulled, which causes duplicate commits and lost work.

bisect performs a binary search across commits while you mark each as good or bad.

reflog records where HEAD has been, including commits dropped by reset.

HTTP/2 multiplexes many streams over one TLS connection, reducing head-of-line blocking from many small asset requests.

The client sends a unique key with a POST

The server hashes or versions a representation and sends it as ETag.

HSTS tells browsers to use HTTPS only, which blocks SSL stripping.

Timers run setTimeout callbacks, then pending callbacks, idle/prepare, poll for I/O, check for setImmediate, and close callbacks.

Backpressure is the signal that a writable destination is slower than the readable source.

Global caches without bounds, event listeners that are never removed, and closures holding large request objects are common causes.

Worker threads share memory and suit CPU-heavy tasks such as image processing inside one process.

An unhandled promise rejection means async work failed with no catch.

Routes only parse HTTP, controllers map requests to use cases, services hold business rules, and a data layer talks to Mongoose.

On SIGTERM stop accepting new connections, finish in-flight requests, close the HTTP server, then close MongoDB and Redis.

A proxy timeout stops hung clients from holding sockets forever.

Attackers can upload huge files, unexpected MIME types, or stored XSS in SVG.

Generate or accept a request id, put it on logs, and return it on error responses.

A replica set is several MongoDB nodes that share the same data, with one primary for writes.

Transactions give ACID across multiple documents on a replica set or sharded cluster.

Write concern decides how many nodes must acknowledge a write, trading durability for latency.