Obviously, trump was familiar with who Boehner was, but trump also has dementia
Trumpkins and some dimwitted talkingheads are using this incident to discredit Wolff's book:
An excerpt from Michael Wolffs upcoming book Fire and Fury: Inside the Trump White House published by New York Magazine on Wednesday claimed that former Fox News head Roger Ailes suggested to Trump the day after the 2016 election that he choose Boehner as his chief of staff.
You need a son of a bitch as your chief of staff, Ailes reportedly told Trump. And you need a son of a bitch who knows Washington. Youll want to be your own son of a bitch, but you dont know Washington.
When Ailes suggested Boehner, Trump reportedly asked: "Who's that?"
http://thehill.com/homenews/news/367247-trump-jr-pushes-back-on-report-trump-didnt-know-who-boehner-was-more-lies
But we've all seen incidents pointing to trump's declining cognitive functioning--his decline has been documented and reported on for over two years now:
Does Donald Trump have dementia? (Death and Taxes, October 2015)
https://www.deathandtaxesmag.com/265291/donald-trump-dementia/
Maybe Donald Trump has really lost his mind: What if the GOP frontrunner isnt crazy, but simply not well? (Salon, April 2016)
https://www.salon.com/2016/04/25/maybe_donald_trump_has_really_lost_his_mind_what_if_the_gop_frontrunner_isnt_crazy_but_simply_not_well/
Scarborough: Trump allies told me he has dementia (The Hill, November 2017)
http://thehill.com/homenews/media/362513-scarborough-trump-allies-told-me-he-has-dementia