Dear Friend, Rottweiller with undocked tail is a recent trend. This breed has always had docked tail as it was used for carrying goods from one place to another. Now, this function of rottweiller is extinct, ie the breed is no longer used to do this function. Thus, Rottweiller in the US have started getting their tails again.
In India, most breeders dock the tails of the puppies when they are born. So getting a puppy with docked tail is not difficult.
Now, when it comes to registration. If the parents of this puppy are KCI registered, then you can easily get the puppy registered as well. For this you need to contact the breeder you bought the puppy from. The certificate will show the pedigree of 5 generation of the puppy. If the puppy belongs to champion line, then the certificate will show CH prefix in front of the name of Sir or Dam.
In case the parents are not registered with KCI, the breeder won't offer the certificate to you. You will have to wait for the puppy to grow atleast 1 year old. You will have to take the puppy to a nominated KCI judge who after examination will sign the relevant form. The photos of the puppy will be signed at the back by him and after that you will have to send them to KCI headquarter Chennai. On receipt of the form and photos, the KCI will issue the papers to you.