# Sentry Keys Explained The Sentry Node is an observation node that monitors the Xai rollup protocol and if an incorrect block is proposed, it raises an alarm (by whatever means its operator chooses) so that others can intervene. The purpose of Sentry nodes is to solve the [verifier’s dilemma](https://medium.com/offchainlabs/cheater-checking-how-attention-challenges-solve-the-verifiers-dilemma-681a92d9948e). Sentry nodes can be run on community members’ laptops, desktops or even on cloud instances. A Sentry Key or Keys are what enable network rewards for running a Sentry Node. A single Sentry Node instance can operate any number of Sentry Keys resulting in one instance generating rewards for unlimited keys. As long as the node is running, there is a probabilistic algorithm that determines if the node operator will receive a esXAI token reward from the network for their Sentry Keys. That algorithm can be increased by staking esXAI. Pool operators run Sentry Nodes for all Sentry Keys staked in their pools. This allows Sentry Key holders to earn rewards without having to operate a Sentry Node. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://xai-foundation.gitbook.io/xai-network/en/about-xai/sentry-keys-explained.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.