As I asked you the first time you posted this, what's the context? Of the two, the first is closer to correct:
At-a-glance Active Directory feature is available.
However, is this a heading or is this part of the text? If it's a heading, it's fine, but if it's a part of the body of the text then it would require an article, probably indefinite, but it could depend on the context.
- For Teachers