user activity / last logged in - six months

Oracle DB: Version 11.2.0.4.8

OS: Linux

RAC: 3 nodes

Auditor's needs to know when was the last time certain users have logged in each Oracle databases. We have 194 users(application users + developers users) in main DB.   I understand that I could create a log in trigger to accomplish this, but what are my other options?

1. is there a DBA_ or v$ view that would show me this information?

2. How could I create an audit that would shows when they last logged in database? I don't want to capture too much information about the user.

any script or syntax would be helpful.

thank you.