I heard there are three diff sunnats of hair..what are they? secondly is getting head shaven a sunnah of Janaab-e- Nabi Kareem (sallahu alahi wasallam) or Hazrat Ali (r.a)?

The hair of Rasulullah (sallallahu alayhi wasallam) reached different lenghts at different times as is evident from the various ahadith. Some ahadith state that the hair of Rasulullah (sallallahu alayhi wasallam) reached till the middle of his ears. Another narration state that it was till the ear lobes. Some state that it reached his shoulders.

Hence it can only be concluded that at different times the lenght was different.

It is proven from many ahadith that Rasulullah (sallallahu alayhi wasallam) did shave his hair on various occasions. However this was not done always.

In Sunan Abi Dawud (Hadith 248) it is stated that Hadrat Ali (radiyallahu anhu) after narrating the hadith of the warning for one who leaves out washing one hair when taking the ghusl of janaba said: "Is is because of this that I have made an enemy out of my head" i.e. he used to always shave his head.

and Allah Ta'ala Knows Best