What steps will you take if the system encounters an overload?

If the system exceeds the allowable load, I would take the following steps:

1. Monitoring and analysis — check load metrics, identify bottlenecks (CPU, memory, network, database).
2. Scaling — add additional server instances (horizontal scaling) or increase resources of existing ones (vertical scaling).
3. Code and query optimization — analyze and improve the performance of critical sections.
4. Caching — implement caching of frequently requested data to reduce database load.
5. Load balancing — configure a load balancer for even distribution of requests.
6. Incoming traffic restriction — implement throttling or rate limiting to prevent overload.

Example of simple rate limiting in Node.js using middleware:

const rateLimit = require('express-rate-limit');

const limiter = rateLimit({
  windowMs: 1 * 60 * 1000, // 1 minute
  max: 100 // maximum 100 requests per IP
});

app.use(limiter);

This approach helps maintain system stability and provides quality service to users.