Learn

What each check looks at, what its answers mean, why they matter, and how to fix what needs it. Every answer in a report links to the part that explains it.

Website

  • Why a website doesn’t loadWhat DNS failures, refused connections, 4xx and 5xx errors, timeouts, and bot checks mean when a website won’t load, and how to fix each.
  • Redirects and HTTPSHow to make http:// switch to https, point www and the bare domain to one address, and fix redirect loops and long redirect chains.
  • Mixed contentWhat mixed content is, why browsers block scripts and styles loaded over http://, and how to find and fix each one.
  • Compression, caching, and page weightHow to send pages compressed with Brotli or gzip, set caching headers, and find the images, scripts, and other sites that make a page heavy.
  • security.txtWhat a security.txt file is, where it goes, which lines it needs, and how to keep its Expires date current.
  • CORSHow CORS preflight requests work, what the Access-Control-Allow headers must say, and how to fix a request a browser blocks.
  • noindex and robots.txtHow noindex and robots.txt keep pages out of search, how to find the rule that blocks a page, and how to remove it.
  • Canonical URLs and hreflangWhat a canonical tag tells search engines, the mistakes that make them ignore it, and how hreflang links a page’s language versions.
  • Title tagsHow long a title tag can be before results cut it short, where to put the brand, and how to write one that matches the page.
  • Meta descriptionsHow a meta description becomes the text under a search result, how long to make it, and what nosnippet and max-image-preview change.
  • FaviconsHow search engines find a site’s icon, the formats and sizes Google accepts, and how to fix an icon that doesn’t show.
  • Open Graph and X cardsWhich Open Graph and X card tags give a shared link its title, description, and image, and how to fix a missing or broken preview.
  • Headings, alt text, and page basicsWhy a page needs one H1, alt text on its images, a viewport tag for phones, and a lang attribute, and how to add each.
  • Structured dataHow JSON-LD tells search engines what a page is about, how to fix a block that doesn’t parse, and which rich results it can lead to.
  • Answer readinessRules of thumb for pages that search features and AI answers can quote: question headings, short answers, lists and tables, figures, authors, and dates.

Certificates

  • SSL certificate errorsWhat a name mismatch, an expired or self-signed certificate, and an incomplete or untrusted chain mean, and how to fix each one.
  • Certificate renewalWhen a certificate should renew, why short-lived certificates are normal, and what to check when one is close to expiring.
  • TLS versionsWhich TLS versions a server should accept, why TLS 1.0 and 1.1 matter mainly for standards, and how to turn them off.

DNS

  • DNS resolvers and propagationWhy DNS resolvers disagree, how TTL decides when a change reaches everyone, and what NXDOMAIN, SERVFAIL, and a dangling CNAME mean.
  • Name serversWhat it means when a name server doesn’t answer, answers without authority, or disagrees with the others, and how to fix a half-done move.
  • DNSSECWhat DNSSEC protects, why broken DNSSEC takes a domain offline for most visitors, and how to fix a DS record that matches no key.
  • CAA recordsHow CAA records choose which certificate authorities may issue for a domain, and how to keep one from blocking your next renewal.

Registration

Email

  • MX recordsHow MX records route a domain’s mail, what happens without one, and when to publish a null MX instead.
  • SPF recordsHow SPF lists the servers allowed to send a domain’s mail, and how to fix a missing record, too many DNS lookups, or a missing include.
  • DKIMHow DKIM signs a domain’s mail, how to find your selector, and what a missing, broken, or revoked key means.
  • DMARCHow DMARC tells receivers what to do with mail that fails SPF and DKIM, how to go from p=none to reject, and how to fix a broken record.
  • MTA-STS and encrypted emailHow MTA-STS and TLS-RPT make sending servers use encryption, how to publish a policy that covers every mail server, and mail app certificates.