SentinelBot, the crawler behind every Sentinel uptime check, is now a verified bot in Cloudflare's Radar bots directory. If you found this post by searching a user agent string from your access logs, the short version: that traffic is legitimate uptime monitoring, it is documented, and this page explains exactly what it does and how to control it.
What you're seeing in your logs
Every check Sentinel performs identifies itself with the same user agent:
Mozilla/5.0 (compatible; SentinelBot/1.0; +https://sentinel.rootstuff.io/bot)
SentinelBot does not crawl, index, or scrape content. It requests the specific URLs that a Sentinel customer has asked us to monitor, typically the homepage or a health-check endpoint, on a fixed schedule from up to four regions (US East, US West, Europe, Asia Pacific). Request frequency is set by the customer's check interval. The full list of monitoring IP addresses is published on our bot information page.
What "verified" means
Cloudflare maintains a directory of known good bots: crawlers whose operators are identified, whose behavior is documented, and whose traffic patterns Cloudflare has validated. Verification means Cloudflare can positively attribute SentinelBot's requests to us, and Cloudflare-protected sites treat those checks as legitimate monitoring traffic by default instead of challenging them.
For Sentinel customers, that closes one of the most annoying gaps in uptime monitoring: the false "down" alert caused by a bot-protection page. A challenge page returns an unusual status or unexpected content, and an unverified monitor can misread that as an outage. With verification, Cloudflare-fronted sites (a large share of the web) recognize the check for what it is.
You stay in control
Verification identifies the bot; it doesn't grant it access. If you operate a site and don't want SentinelBot's requests, two lines of robots.txt stop it:
User-Agent: SentinelBot
Disallow: /
SentinelBot respects robots.txt. You can also block the published monitoring IPs at your firewall, or use Cloudflare's own bot controls, which let you allow or block any verified bot by name. If you believe SentinelBot is checking your site and shouldn't be (for example, a former vendor left a monitor running), contact us and we'll investigate.
Why we did this
Sentinel's whole job is to tell you the truth about whether a site is up. Every layer between our checkers and your server that might challenge, delay, or rewrite a request makes that truth blurrier. Getting SentinelBot verified is part of making our checks boring and predictable: documented user agent, published IPs, robots.txt compliance, and now third-party attribution from the network that fronts much of the web.
You can see SentinelBot's live traffic profile on Cloudflare Radar, and everything else about the bot on our bot information page.