Sgt Namer's funeral is due to be held in Israel today.
The Israeli-born soldier was one of the more than 50 Israeli victims of the conflict in the Middle East that's also claimed more than 400 Lebanese lives.
Sgt Namer was killed in a Hezbollah ambush near the guerrilla stronghold of Bint Jbeil in southern Lebanon on Wednesday.
He had moved to Australia with his mother and sister Karin when he was 12.
Moriah College student
About 350 students and teachers at Moriah College, in Sydney's eastern suburbs, today held a memorial service to commemorate Sgt Namer, who graduated from the school in 1997.
The service also was attended by distraught members of Sgt Namer's family and a number of friends.
Wayne Kahn, who went to school with Sgt Namer, remembered him as a "sweet, shy kid who was always happy and loved to play basketball".
He said Sgt Namer had planned to visit Australia on his discharge from the Israeli Defence Force.
School friend Richie Harkham, 27, said former classmates gathered last night to mourn their friend's death.
He said Sgt Namer was committed to Israel, but loved Australia as the place he had spent his formative years.
"He believed a lot in Israel and what he was doing," Mr Harkham said. "He loved Australia so much as well, but he remembered where he came from, he represented all of us.
"We all truly believe in Israel and we support it from here, but Asaf was on the front line and actively supporting the cause."
During today's service, Moriah principal Roy Steinman sang the traditional Jewish memorial prayer and paid tribute to the "talented graphic artist" who had loved basketball, his chosen sport.
Family leave for Israel
Mrs Namer and her daughter Karin have flown out of Sydney bound for Tel Aviv, to attend the soldier's funeral. With them was Sgt Namer's uncle, Danny Morgenstern.
"I cannot believe it," Mrs Namer told the Australian Jewish News (AJN) before she left.
"I spoke to him on Sunday and he said they were moving him to another place. I called his mobile on Monday but I couldn't get through.
"I still think maybe it was not him. He was only a month away from finishing his army service."
Karin Namer said her father Yitzchak, who lives in Israel, rang her with the news early in the morning.
"It was my father on the line but I didn't recognise his voice. He said my brother had been killed. I was in a state of shock," she told the AJN.
"I thought they had got something wrong. In everything he did he had to be the best. My brother was an absolute hero."
A dual Australian-Israeli citizen, Sgt Namer returned to Israel two-and-a-half years ago and volunteered to join the army.
His burial is expected to take place today before the start of the Jewish Sabbath.
Australian Foreign Minister, Alexander Downer, has confirmed Sgt Namer’s death saying he was in the last month of his Israeli national service.
Returned to Israel
Sgt Namer enlisted in the Golani infantry unit when he returned to Israel.
When not on duty, he lived with his girlfriend, Revital, in Tel Aviv, and they were planning to settle down together, Israel's Yediot Achronot newspaper said.
Sydney man Danny Senecky, 26, said his close friend and former schoolmate was a "lovely very, very kind hearted bloke - nothing was too much of a problem. He was my best mate who was always there."
Sgt Namer had gone to Israel specifically to join the army, he said.
"He didn't get into the elite combat unit he wanted, but was happy where he was," Mr Senecky said.
"When he went away, as an Australian Jew to go and serve in the Israeli army, it's something a lot of people aspire to, not many get around to it."
Jewish community mourn
Sydney's Jewish community also mourned his death. "We were extremely upset to hear about the death as we are at all casualties of this war," said NSW Jewish Board of Deputies chief executive Vic Alhadeff.
In Kiryat-Ata, north of Haifa, where Sgt Namer's father and grandmother lived, officials paid tribute to the Australian who had sacrificed a quiet life in Australia to fight for Israel.
"Although his life was in Australia, he was a Zionist who chose to come to Israel in order to do his part," mayor Yaakov Peretz told the Yediot Achronot.
Australia's opposition leader Kim Beazley also expressed his sympathy over Sgt Namer's loss. "He was obviously fighting for something that he believed in," Mr Beazley said.