Is it DNS?
Two DNS queries, run here or in your own terminal.
0installs
0scripts
0accounts
2queries
via Cloudflare DoH
macOS / Linux (dig)
Windows (PowerShell)
nslookup (anywhere)
1. Is your answer being rewritten?
Asks canary.probe.isitdns.net, which answers 192.0.2.111.
$ dig +short canary.probe.isitdns.net
PS> (Resolve-DnsName canary.probe.isitdns.net -Type A).IPAddress
$ nslookup -type=A canary.probe.isitdns.net
good: 192.0.2.111
anything else: your DNS answer was rewritten in flight
2. Did your query reach the authority?
Asks a fresh random label under t.probe.isitdns.net.
$ N=$(LC_ALL=C tr -dc 'a-z2-7' < /dev/urandom | head -c26)
dig +short TXT x$N.t.probe.isitdns.net
PS> $N = -join ((97..122) | Get-Random -Count 26 | % {[char]$_})
Resolve-DnsName -Type TXT "x$N.t.probe.isitdns.net" | % Strings
$ nslookup -type=TXT xk4m2vqz7ftr3nbwhs6ydc5gpjq.t.probe.isitdns.net
Change a few letters first, from a-z2-7, same length.
good: a base64url TXT string comes back
empty or SERVFAIL: your path never reached the authority