Hi,

There are multiple contacts attached with the domain name registration... like "registrant", "admin", "technical", "billing" etc...

Can any one tell me who is the owner of the domain name out of these contacts? And how should other contacts be honored ?

registrant is the owner, period...

That's true ... but what if i receive a billing related request from admin contact ... should I honor that ?

The admin contact is an authorised contact for the domain so if the admin contact has a billing query then there is normally no reason why you can't deal with him/her - unless your own terms and conditions, as a hosting provider, state that you will only deal with the person with whom you have entered into a contract.

With domain name transfers it's the admin contact address that has to deal with all the approval messages.