That seems to happen when you put in a DNS target that doesn't have any records in SecurityTrails. In that case, it is best to use nslookup
Re:Issues with upstream DNS provider
by jonathanreinink on Tuesday August 23, 2022 @08:40PM
(#32573587)
Yeah securitytrails.com was working for me, but went down about 10 mins ago.
EDIT: I MANAGED to make it work with this:
https://www.nslookup.io/
Make sure to go through all the tabs at the top (Cloudflare DNS, Google DNS) - for me they were all "no A records found". Only "Authoritative" gave me 3 A records which I successfully managed to use.