Mini Tools

Read a server check

A server check returns the status, server response time, certificate, DNS, network and domain expiry. What each field means, and why the country can mislead.

Read a ping result

A ping test reports five numbers, and the average is the least useful of them. Read a ping result properly, with real measurements from our five regions.

Read a traceroute output

A traceroute online shows every hop, its round trip times and the network that owns each one. Read a trace, find the bad hop and know what it cannot tell you.

Check a TLS certificate

A TLS certificate check verifies the chain, the name and the dates, and nothing more. What each result means, and the failures a valid certificate hides.

Tell whether you have IPv6

An IPv6 test answers two questions. Does your own connection speak IPv6, and does your site answer on it? How to read the result, and why it matters now.

Look up a MAC address

A MAC address vendor lookup names the organization behind a hardware prefix and nothing else. What it cannot tell you, and why modern devices return no vendor.

Test what robots.txt blocks

A robots.txt allow and disallow rule decides whether a crawler may fetch a URL, and nothing else. How the decision is made, and why a blocked page still ranks.

Find the broken links on a site

A crawl reports twelve counters, and the 404s are not the expensive ones. What each figure means, and why a page returning 200 can be the worst result of all.

Validate a sitemap

The sitemap limits that break a file, the fields Google ignores, and the URLs that vanish with no error. Validate against the protocol and know what to change.

Read a link graph

An internal link graph shows how your pages point at each other. What the counters mean, the two kinds of orphan, and why click depth is a guideline not a rule.

Read a DNS lookup

A DNS lookup asks four public resolvers in each of five regions what a record says. Read the consensus check, the TTL spread and the resolver tables.

How DNS propagation works

DNS propagation is twenty resolver caches expiring on their own schedule. What a TTL bounds, how to plan a change, and why a missing record is cached too.

Which check do I need

A map of the checks, ordered by symptom rather than by tool. Something is slow, something is down, search traffic fell, or you do not know what a device is.