# Hedged requests

> A Link sends a second copy of a slow call after the p95 and keeps the faster answer: the tail drops and the callee sees 10% more calls.

## Prerequisites

Research these first: [Distributed tracing](https://wiki.playquorum.dev/research/tracing.md).

## Engineering terms

- [Hedged request](https://wiki.playquorum.dev/glossary/hedged-request.md)
- [Tail at scale](https://wiki.playquorum.dev/glossary/tail-at-scale.md)

## Facts

Hedged requests
- **Track:** Reliability
- **Era:** [Series C](https://wiki.playquorum.dev/eras/series-c.md)
- **Cost:** 16.7k 16.7k 16.7k 50.0k
- **Requires:** [Distributed tracing](https://wiki.playquorum.dev/research/tracing.md)

## See also

- [Research tree](https://wiki.playquorum.dev/research.md)

Source: https://wiki.playquorum.dev/research/hedged-requests