About the domains and network tools
This group looks at the plumbing behind a website and behind your own connection. Some tools read public records about a domain or an IP address: where its DNS points, who registered it, which certificate it presents and which servers take its email. Others measure the link between your device and our server.
They are aimed at people who look after domains and email, such as site owners, IT staff and developers, and at anyone trying to work out whether a problem lies with their internet or with a site. The record lookups run from our server, in one location, so they show what that location sees.
Where to start
For a domain, begin with the DNS Lookup, which can show A, AAAA, CNAME, MX, NS, TXT, SOA and CAA records together. After you change a record, the DNS Propagation Checker compares the answers public resolvers give, to show where the change has arrived. The SSL Certificate Checker reads the certificate a site presents and counts the days it has left, and the WHOIS Lookup asks the registry for the registrar and the key dates.
For email, the MX Record Lookup lists mail servers in priority order and the SPF & DMARC Checker reviews SPF, DMARC and DKIM. For an IP address, the IP Address Lookup shows who it is registered to, and the Reverse DNS Lookup finds the hostname it publishes.
If you suspect your own connection, Is It My Internet? times round trips from your browser to our server and gives a plain answer in seconds, and the Internet Speed Test measures download and upload speed. What Is My IP shows the public address our server sees when you visit, and the Port Scanner checks which TCP ports on an address accept connections from our server.