How do I know if an expired domain is worth?

Well, this will be my first time when I'm gonna buy an expired domain.
So how do I know his "seo" history? How could I know if it's "banned" or was deindexed by google, etc?

that domain is having lots of backlinks that I like, nice authority, etc.

Checking with semrush, I've seen the domain got lots of backlinks pointing to subdomains - seo.domain.com, link.domain.com, bhw.domain.com and so on.

BUT!

when I checked, only seo.domain.com is indexed in google - so domain.com is not indexed.
will be this an issue?

If I buy the domain, will I need to create those subdomains and then make a 301 redirect to root?

Thank you.

I really needsome advices.

Well yeah, a subdomain is basically a full domain on it's own, meaning that if sub.domain.com ranks that doesn't mean domain.com does.

isshmen said:

I really needsome advices.

Click to expand...

Read this by @Nargil
https://www.blackhatworld.com/seo/what-is-your-checklist-for-domains-for-pbn.1342695/post-14514468
Also @splishsplash has threads on these topics.

ReaL_GainZ said:

Well yeah, a subdomain is basically a full domain on it's own, meaning that if sub.domain.com ranks that doesn't mean domain.com does.

Click to expand...

I know.

but it is possible for that domain to have indexed the subdomain but not the root?
that' my big question.