Who was guru of Drupad putra Dhrishtadyumna

Drona was the Guru for Pandavas and Kavravas. But Arjuna was his favourite student. In the Mahabharatha Battle Drona asked both Pandavas and Kauravas to capture King Drupada alive and give to him as their Gurdhakshina. This he asked to humiliate Drupada (father of Drupathi -wife of Pandavas) due to a old enmity, which I have narratted below. Finally Arjuna only fulfilled his order as a Gurudakshina. He brought drupada duly tied with ropes and presented to Drona. Chakravarti C Rajagopalachari appreciated Arjun's devotion to Guru, in his Mahabaratha story.

Now the details of old enmity between Drona and Drupada -

Drupada, also known as Yajnasena, was the king of the land of Panchala.

In his youth he studies with, and becomes a friend of Drona. Drona makes him promise to share all his fortunes with him. Later, when Drupada becomes king of Panchaladesa, Drona reminds him of his promise and asks for wealth. Drupada mocks Drona for taking a promise made in their irresponsible days of youth. Deeply angered, Drona becomes the teacher of the Kuru princes of Hastinapura. After their education is complete, Drona asks them to defeat Drupada. In a surprise attack, Arjuna, the Pandava, disarms Drupada and forces him to surrender a part of his kingdom.

Drupada is father to the reborn Amba, who is known as the man Shikhandi, but who was born as a girl, sometimes known as Shikhandini.

In his quest to gain revenge on Drona, Drupada, with the aid of the devas, fathers Draupadi and Dhrishtadyumna, the latter finally killing Drona. Drupada himself is killed by Drona during the great Mahabharata war.