Jordan Hugill levelled in the 89th minute after Tom Lawrence had put the visitors in front at Deepdale in the first half.
PNE boss Grayson said: "It was always going to be a tough game when you are up against Mick McCarthy's team you know they are going to be resilient.
"Our performance wasn't one of the best with the ball in terms of the creative side of it but we kept plugging away, kept asking questions.
"When you saw the blocks Ipswich put in and the saves their goalkeeper made, maybe you thought it wasn't going to be our day.
"Ultimately we kept going and got our just rewards.
"In the last few minutes you hoped we might go on and score a winner but overall a draw was a fair result."
Hugill had been subject of two failed bids from Ipswich, the latest for Â£2m a few days ago.
This was his third goal in two games following a double against Aston Villa.
"We just want Jordan to keep scoring goals and his value will go up," said Grayson.
"I spoke to him before the game because I didn't want speculation to affect his performance.
"I don't think it affected him because he played well, he held up the ball really well and gave their back four a tough time.
"For the goal we had plenty bodies up there, it might not have been the prettiest of build-ups but it was a great finish from Jordan.
"It was good for him to build off last week's two goals."
Grayson confirmed after the game that North End would be bringing a defender on Monday, in time to travel with the squad to Cardiff City for Tuesday night's clash.
He said: "We will be signing a defender in the next 24-48 hours, the lad will join-up with us on Monday and travel to Cardiff."