SecurityTrails has a SQL like advanced query syntax you can use to more accurately retrieve the data you require. It's modeled off of SQL 'where' predicates. You can read more about the available fields and syntax on our docs and here's some sample queries to get you started.
Example queries
apex_domain = "google.com"
Return all results associated with the apex domain google.com
apex_domain = "facebook.com"
Return all results associated with the apex domain facebook.com
subdomain = "www"
Return all results with that are www subdomains.
subdomain = "mail"
Return all results with that are mail subdomains.
apex_domain = "google.com" or apex_domain = "amazon.com"
Return all results associated with google.com OR amazon.com
(subdomain = "www" or subdomain = "mail") and ipv6 != null
Return all results that are either www or mail subdomains and have an IPv6 IP associated with them