NL25rush AK turn play

[babyonboard]

$0.10/$0.25 No Limit Holdem
FullTiltPoker (http://weaktight.com/ftp/)
6 Players
Hand Conversion Powered by weaktight.com (http://weaktight.com/)

Stacks:
UTG IROAM HARD ($15.73)
UTG+1 Hero ($29.14)
CO chippie89 ($26.37)
BTN ITILTYOUBIG ($31.21)
SB KvaziBaza ($154.61)
BB hatesspades ($73.47)

Pre-Flop: ($0.35, 6 players) Hero is UTG+1 :ac: :kd:
1 fold, Hero raises to $0.75, 1 fold, ITILTYOUBIG calls $0.75, KvaziBaza calls $0.65, 1 fold

Flop: :6h: :ad: :5d: ($2.50, 3 players)
KvaziBaza checks, Hero bets $2, ITILTYOUBIG calls $2, KvaziBaza folds

Turn: :2h: ($6.50, 2 players)
Hero bets $4.25, ITILTYOUBIG raises to $10, Hero

what is the best play v an unknown?

[Lev729]

Bet/fold is perfectly fine. He called in a 3way flop and almost miniraised OTT, so probably he had a strong range.