Follow
Naidu
Nayaka->Nayudu-> Naidu->Naicker->Naidoo
(Once we were warriors)
Captain or headman. Were known as protectors of Caravans especially those passing through the Deccan. Thus associated with the military. origins. Title of honour among Hindus in the Deccan. "The kings of Deccan also have a custom when they will honor a man or recompense their service done, and raise him to dignity and honour. They give him the title of Nayak."
It evolved in the following manner during different phases of history.
Many people with the Naidu surname had some remote ancestor who was a soldier that was promoted to "Nayaka". It is equivalent to a Baron. They served as Nayaks under various Emperors. During times of peace - they were agriculturalists, tradesmen and merchants.
Source: http://www.kapusangam.com/history.php
Cannot say whether true or not, but does appear to be a popular explanation.\