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Knowledge Base & Operational DocumentationDomains, DNS & Business Email
Why Does a Domain Load the Website but Fail Certificate Renewal?
A website can remain available with an existing certificate while automated renewal fails because DNS validation points elsewhere, a challenge path is blocked, or the certificate authority sees a different server. What to check Check renewal logs, authoritative DNS, HTTP challenge path, proxy behavior, domain aliases, and certificate coverage. Verify...
Why Does a Business Website Work Internally but Not From the Internet?
Internal access may use private DNS, a VPN, or a local network route that bypasses public DNS and firewall rules. External visitors can fail even while employees see a working site. What to check Compare internal and public DNS answers, public IP and NAT, firewall rules, load balancer health, TLS certificate, and server logs. Confirm the public route...
Why Does a Website Redirect to an Unfamiliar Subdomain?
An unexpected subdomain redirect can result from stale canonical settings, a compromised application, control-panel redirect rules, proxy configuration, or cached response headers. Visitors may land on a site that does not match the intended brand. What to check Trace the full redirect chain with response headers, check application base URLs, DNS and...
Why Does Business Email Stop Working After a Web Hosting Move?
A website move can also change nameservers or DNS records, unintentionally redirecting or removing mail routing. Web traffic may recover while MX, SPF, DKIM, or autodiscover records remain wrong. What to check Compare current authoritative zone with the previous zone, check MX targets and mail host status, review nameserver changes, and inspect bounce...
Why Does a Website Load With www but Redirect to the Wrong Domain?
A www hostname can resolve correctly yet redirect to an old or unexpected domain due to application canonical settings, registrar forwarding, proxy rules, or cached permanent redirects. What to check Trace each redirect response and check DNS, registrar forwarding, web server virtual hosts, application base URL, proxy configuration, and cache headers....
Why Do Some Recipients Get Email While Others See a Delivery Delay?
Different recipient providers can apply different throttling and reputation checks. A delayed message may be queued or temporarily deferred even while other destinations accept mail. What to check Review the full delivery log and SMTP response for affected recipients, sending volume, SPF/DKIM/DMARC alignment, reverse DNS, and recent DNS changes. Do not...
Why Does a Domain Work on Wi-Fi but Not on a Mobile Network?
A domain that resolves on one network but not another may be affected by cached DNS, different resolvers, IPv6 records, or a recent nameserver change. What to check Compare DNS answers and TTLs on both networks for A, AAAA, and CNAME records. Check authoritative nameservers and test whether the problem affects the apex, www host, or a specific service....
How to Find an Old DNS Record That Keeps Returning After You Remove It
A deleted record can appear again when it still exists at another authoritative nameserver, is managed by an automated integration, or remains in a local or resolver cache. What to check Query each authoritative nameserver directly, check registrar delegation and DNS provider automation, and compare TTLs with cached results. Confirm the exact hostname...