absolutely.
distinguishes between the two cases.
1. Different second-level domain names can be used for the same first-level domain name, such as abc.com, for different projects, such as 1.abc.comjournal 2.abc.com
2, and different projects for the same domain name, such as www.abc.com/web,www.abc.com/api, as long as webserver is configured, such as nginx's rewrite rules.

of course, the second case is more helpless.

Yes, you can create a second-level domain name

you can divide a domain name into different folders, or you can do a second-level domain name pointing to

Port distinction

can multiple projects share the same domain name?
answer: you can use one domain name, but not under the same address. This is a logical problem, which means that multiple projects can have www.test.com and api.test.com manage.test.com domain names, but not in www.test.com at the same time. Otherwise, which one should be visited during access?

and why it is more secure to use a domain name
answer: domain name security is that it hides the server ip address. Of course, this is not useful for people who know a little bit of technology, but at least be safe.
if it is not an internal project, the use of the domain name is convenient for users to remember, and the other is to facilitate the inclusion of search engines. And the ssl (https) certificate can only be installed under the domain name, not under ip

Yes but not the same path