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DNS lookup See the A records a domain resolves to. MX lookup See which servers handle a domain's email. NS lookup See which nameservers are authoritative for a domain. TXT lookup See every TXT record on a domain. CNAME lookup See what a subdomain points at. CAA check See which authorities may issue certificates for a domain. Reverse DNS lookup Find the hostname an IP address answers to. SPF check See which servers are allowed to send email as a domain. DMARC check See what a domain tells receivers to do with email that fails checks. BIMI check See whether a domain publishes a logo for email clients to show. HTTP header checker See exactly what headers a page sends back. Redirect checker Follow a URL through every redirect to where it ends up. robots.txt analyser See which crawlers a site allows and blocks. HTTP/2 test Find out which HTTP version a site negotiates. Open Graph checker See how a page looks when it is shared on social media. Sitemap checker Find a site's sitemap and check it parses. SSL certificate checker Check a certificate is valid, current and covers the right names. HSTS checker Check a site tells browsers to insist on HTTPS. Ping test Check a server is reachable and see how quickly it answers. Port checker See which standard web and mail ports are open on a server. WHOIS lookup See who a domain is registered with and when it expires. Domain age checker Find out how long a domain has been registered. AI agent readiness See how well an AI agent can navigate and act on your site.