What is Domain: Domain is a name of website for example tesla.com.
What is Subdomain: is a part of a larger domain name that helps organize or separate different sections of a website. For example shop.tesla.com.
How to find subdomain:
Passive Subdomain: Passive Subdomain means most of them they some alive and some dead. some website for given subdomains.
Simply open google and write crt.sh and write any target domain for example i write tesla.com. show this type subdomains and this ipaddress.
This type of subdomain is show and copy of them and paste on https://comparetwolists.com/ for remove all duplicate subdomains. And this is not simply copy all subdomains so, simply download extension on google ublock origin extension.
And, next website is https://dnsdumpster.com/ simply open and write target domain and collect all subdomain and copy and paste on https://comparetwolists.com/ and remove all duplicates subdomains.
And check of them all subdomains easily this and others different google search engine through domains. And sure prectice is more important of all of them. GOOD BYE……………………………………..