Ali Bunney, 20, was found unconscious at the edge of Gloucestershire Airport last February. He died later.
He was an economics and accounting undergraduate at Cardiff University.
Gloucestershire coroner Katy Skerrett said Mr Bunney's was "a tragic death and a short-form conclusion will be an alcohol-related death."
But speaking after the inquest, Mr Bunney's parents, Nigel and Marissa, questioned the coroner's findings.
"There [are] a lot of unanswered questions," Mr Bunney said.
His wife added: "I don't believe he walked all that way. It's a mother's instinct. I don't believe he walked four miles in an hour - someone has dumped him there.
"I always pray for him and pray for justice for Ali."
Ms Skerrett concluded the various medical teams did all they could to save Mr Bunney and there was "no unnecessary delay at any stage" in treating him.
"This was a young man who had been out drinking with friends and had a very good, fun evening," she added.
"For whatever reason, he chose to depart from the plans of going back to a friend's house and it seems more likely than not that he was trying to make his way home.
"Due to the amount of alcohol he had consumed and this was a very cold and wet night - both those two factors got the better of this young man, which led to him being found."
The inquest at Gloucestershire Coroners Court was told Mr Bunney could have been more than four times the drink-drive limit when he left a town centre nightclub to walk the nine miles to his home wearing just a short-sleeved shirt and trousers in temperatures as low as 4C (39F).
He had been out in Cheltenham on the night of 8 February last year with a group of people celebrating his friend's 21st birthday. He was days away from celebrating his own 21st birthday.
The inquest was told the student had eaten a meal and friends described seeing him drinking pints of lager, glasses of cocktails and shots of spirits during the night out, which ended at a nightclub.
Friends described him as "staggering" and "swaying from side to side" and when he vanished from the Subtone club they tried to ring him but could not get hold of him.
The inquest heard dog walker Keith Wilson found Mr Bunney lying on his back.
Mr Wilson alerted a fire crew at the airport, who quickly arrived at the scene, and called for assistance from the ambulance service.
Mr Bunney was taken to Gloucestershire Royal Hospital where he was later confirmed dead.
A drunk student died from hypothermia after walking home from a night out in Cheltenham in shirtsleeves in winter, an inquest has heard.