# Services from sentinel.rootstuff.io on Zero

> sentinel.rootstuff.io serves 14 paid API services for AI agents, indexed by Zero. Each is callable per call with payment handled by Zero.

Canonical page: https://www.zero.xyz/host/sentinel.rootstuff.io
Live health (JSON, refreshed every minute): https://www.zero.xyz/host/sentinel.rootstuff.io/health.json

## Services

- [Sentinel DNS Propagation Checker](https://www.zero.xyz/c/sentinel-dns-propagation-checker-24de3cf4/llms.txt): $0.01/call via x402. Retrieves every DNS record of a specified type for a domain and checks propagation status across multiple public resolvers
- [x402 Payment Challenge Inspector](https://www.zero.xyz/c/x402-payment-challenge-inspector-74c262f6/llms.txt): $0.02/call via x402. Fetches and returns the 402 payment challenge (payment envelope) from a paid HTTP endpoint without actually paying it
- [Sentinel Dead-Man Switch](https://www.zero.xyz/c/sentinel-dead-man-switch-129ae93c/llms.txt): $0.05/call via x402. Registers a dead-man switch that issues a signed callback to your URL if heartbeats stop arriving within the specified timeout window
- [Sentinel 6-Hour URL Watcher](https://www.zero.xyz/c/sentinel-6-hour-url-watcher-f73700f4/llms.txt): $0.2/call via x402. Monitors a public URL for 6 hours and delivers signed webhook callbacks whenever its up/down verdict changes
- [Sentinel Security Header Inspector](https://www.zero.xyz/c/sentinel-security-header-inspector-299aeac2/llms.txt): $0.01/call via x402. Fetches response headers from a URL and reports on the presence and quality of HTTP security headers
- [Sentinel 24-Hour URL Watcher](https://www.zero.xyz/c/sentinel-24-hour-url-watcher-8eb3f546/llms.txt): $0.5/call via x402. Monitors a public URL for 24 hours and delivers signed webhook callbacks whenever its availability/verdict changes
- [Sentinel URL Watcher (1-Hour)](https://www.zero.xyz/c/sentinel-url-watcher-1-hour-da1d9a2a/llms.txt): $0.05/call via x402. Monitors a public URL for 1 hour and sends signed webhook callbacks whenever its reachability or status verdict changes
- [Sentinel Timer – Scheduled Signed Callback](https://www.zero.xyz/c/sentinel-timer-scheduled-signed-callback-e09ef70c/llms.txt): $0.01/call via x402. Schedules a single signed HTTP POST callback to a specified URL at a chosen future time or after a delay, echoing back a custom JSON payload.
- [Sentinel SSL Certificate & TLS Handshake Grader](https://www.zero.xyz/c/sentinel-ssl-certificate-tls-handshake-grader-738e7344/llms.txt): $0.01/call via x402. Retrieves the TLS certificate details and handshake security grade for a given public hostname on port 443
- [Sentinel Redirect Chain Tracer](https://www.zero.xyz/c/sentinel-redirect-chain-tracer-8e78c3ef/llms.txt): $0.01/call via x402. Follows a URL through its full redirect chain and returns each hop up to the final destination
- [Sentinel ICMP Ping Latency & Packet Loss](https://www.zero.xyz/c/sentinel-icmp-ping-latency-packet-loss-bf4dd5c7/llms.txt): $0.01/call via x402. Measures ICMP ping round-trip latency and packet loss for a given hostname or public IP address
- [Domain Registration Expiry & Registrar Lookup](https://www.zero.xyz/c/domain-registration-expiry-registrar-lookup-f5be8386/llms.txt): $0.01/call via x402. Returns the registration expiry date and registrar information for a given domain name
- [Sentinel URL Consensus Checker](https://www.zero.xyz/c/sentinel-url-consensus-checker-a2a9febb/llms.txt): $0.02/call via x402. Runs a four-region distributed consensus probe on a URL to verify its reachability and behavior
- [Sentinel TCP Port Reachability Checker](https://www.zero.xyz/c/sentinel-tcp-port-reachability-checker-36f7fa4e/llms.txt): $0.01/call via x402. Checks whether a specific TCP port on a host is reachable and measures the connection latency

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

- [Zero catalog index](https://www.zero.xyz/llms.txt)