--- title: How Oh Dear identified a certificate problem at a large... description: Oh Dear's SSL certificate monitoring checks every 30 minutes per site, which allowed it to detect a misconfiguration at a large CDN provider where some edge... canonical: https://daily.dev/posts/how-oh-dear-identified-a-certificate-problem-at-a-large-cdn-provider-3vauwd4yo twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: How Oh Dear identified a certificate problem at a large CDN provider | daily.dev og:description: Oh Dear's SSL certificate monitoring checks every 30 minutes per site, which allowed it to detect a misconfiguration at a large CDN provider where some edge... og:url: https://daily.dev/posts/how-oh-dear-identified-a-certificate-problem-at-a-large-cdn-provider-3vauwd4yo og:image: https://api.daily.dev/og/posts/3VAUWd4Yo.png og:image:alt: How Oh Dear identified a certificate problem at a large CDN provider og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # How Oh Dear identified a certificate problem at a large CDN provider **[Oh Dear](https://daily.dev/sources/ohdear)** · 5 min read · 0 upvotes · 0 comments ## Summary Oh Dear's SSL certificate monitoring checks every 30 minutes per site, which allowed it to detect a misconfiguration at a large CDN provider where some edge servers were returning their own wildcard certificate instead of the customer's certificate. The post explains how the issue was discovered through SNI-based certificate fetching, how Oh Dear improved its tooling to expose the specific IP address used during checks, and how they collaborated with the CDN provider to identify and fix two misbehaving edge servers across thousands worldwide. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Bring your own certificate to your status page](https://daily.dev/posts/bring-your-own-certificate-to-your-status-page-lvpbdyh2u) · Oh Dear · 0 upvotes · 0 comments - [Connect any AI assistant to your Oh Dear data](https://daily.dev/posts/connect-any-ai-assistant-to-your-oh-dear-data-wwo7byape) · Oh Dear · 0 upvotes · 0 comments - [The effects of the Cloudflare outage on Oh Dear](https://daily.dev/posts/the-effects-of-the-cloudflare-outage-on-oh-dear-ryctrjryu) · FREEK.DEV · 2 upvotes · 0 comments - [Using Oh Dear to monitor your API responses](https://daily.dev/posts/using-oh-dear-to-monitor-your-api-responses-gr57txgjw) · Oh Dear · 0 upvotes · 0 comments --- Tags: [#security](https://daily.dev/tags/security) [View this post on daily.dev](https://daily.dev/posts/how-oh-dear-identified-a-certificate-problem-at-a-large-cdn-provider-3vauwd4yo) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"How Oh Dear identified a certificate problem at a large CDN provider","url":"https://daily.dev/posts/how-oh-dear-identified-a-certificate-problem-at-a-large-cdn-provider-3vauwd4yo","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/how-oh-dear-identified-a-certificate-problem-at-a-large-cdn-provider-3vauwd4yo"},"datePublished":"2026-07-13T06:52:32.746Z","dateModified":"2026-07-13T06:52:53.086Z","description":"Oh Dear's SSL certificate monitoring checks every 30 minutes per site, which allowed it to detect a misconfiguration at a large CDN provider where some edge...","image":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/844b59e0f0ed71d0e912f5df4d7edd33?_a=AQAEuop","thumbnailUrl":"https://media.daily.dev/image/upload/f_auto,q_auto/v1/posts/844b59e0f0ed71d0e912f5df4d7edd33?_a=AQAEuop","isAccessibleForFree":true,"articleSection":"Oh Dear","inLanguage":"en","publisher":{"@type":"Organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180}},"author":{"@type":"Organization","name":"Oh Dear","logo":"https://media.daily.dev/image/upload/s--ZL1kyzYt--/f_auto,q_auto/v1780213613/logos/ohdear?_a=BAMAMiWQ0","url":"https://daily.dev/sources/ohdear"},"commentCount":0,"discussionUrl":"https://daily.dev/posts/how-oh-dear-identified-a-certificate-problem-at-a-large-cdn-provider-3vauwd4yo","interactionStatistic":[{"@type":"InteractionCounter","interactionType":{"@type":"LikeAction"},"userInteractionCount":0},{"@type":"InteractionCounter","interactionType":{"@type":"CommentAction"},"userInteractionCount":0}],"keywords":"security","timeRequired":"PT5M"} {"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https://daily.dev"},{"@type":"ListItem","position":2,"name":"Oh Dear","item":"https://daily.dev/sources/ohdear"},{"@type":"ListItem","position":3,"name":"How Oh Dear identified a certificate problem at a large CDN provider"}]} ```