About Question enthuware.jwpv6.2.892 :

[deadlock_gr]

Is the answer to this correct?

I think that the realm is independent of the login mechanism. It simply defines users, groups and group memberships.

[admin]

Yes, it is correct because when you use the "basic" authentication mechanism, you are presented with a "realm" within which your credentials are relevant. This is as per http://www.ietf.org/rfc/rfc2617.txt

HTH,
Paul.

[deadlock_gr]

In the link you specify, it says:

"The realm directive (case-insensitive) is required for all authentication schemes that issue a challenge."

In other words, regardless the way you give your credentials (BASIC, Form etc), those credentials will be validated against a realm.

[admin]

You are right. I misunderstood it. Thanks for pointing it out.
All except client-cert. Client-cert doesn't issue a challenge.