Knowledge base
Understand the checks, diagnose problems and verify your changes.
How to read a check.uk.app report
Turn diagnostic observations into a useful next step.
SSL errors: expiry, hostname and certificate chain
Find the cause before replacing your TLS configuration.
Check Gzip and Brotli; configure Gzip in Nginx
Verify the actual response instead of assuming that compression is enabled.
HTTP/2 and HTTP/3: confirmed support versus a timeout
Understand what a successful protocol connection actually proves.
Fix redirect loops: HTTPS, www and reverse proxies
Find the conflicting rule and verify the complete route to your page.
Security headers: understand the results
Review policy values and missing headers without breaking legitimate site features.
Introduce CSP with Report-Only: a practical rollout
Observe violations, test essential journeys and enforce only the policy you have verified.
SPF, DKIM and DMARC: records, alignment and delivery
Choose the correct domain and selector, interpret DNS findings and investigate undelivered mail.
robots.txt and noindex: diagnose crawling and indexing blocks
Separate crawl permission from indexing instructions and inspect the exact URL.
Sitemap errors: XML, server responses and page URLs
Find whether the problem is fetching the file, parsing it or selecting the right pages.
IPv4 works but IPv6 fails: a diagnostic checklist
Separate DNS publication, probe connectivity and the website’s IPv6 service.
