I have got my tickets. I am travelling from Auckland to Mumbai with a transit in Dubai. I have 4 hours of transit time. I will be coming by Emirates EK 449 and leaving on Emirates EK 506. I don't know the arrival gate and the departure gate. I only know that both will be in the same terminal, thats terminal 3. How large is this terminal and what is the maximum amount of time that it might take to get from one gate to another? Also, during the transit, is there a possibility that a bus/train needs to be taken?
Concourse and gate numbers aren't assigned far in advance, so we can't give you the gate numbers now. Before departure, you can check your connection information on the airport website, though it is always subject to change, so check the TV monitors after you arrive in Dubai for the latest information about your next flight.
Terminal 3 is extremely large, as in "was the largest building in the world by floor space" large. It is divided into three parts: Concourses A, B, and C, but all three concourses are connected. However, the airport is well-designed to facilitate connecting passengers, and there are signs and staff to guide you.
Upon arrival, you'll go through a security check and then can follow signs to your gate. Concourse A is connected to concourse B by a short train trip. There is a bus that connects Concourse A and Concourse C to save you the walk all the way across Concourse B. Signs will direct you to the bus/train/walkway as appropriate.
Four hours is far more than enough time unless your flight is significantly delayed, at which point you should ask airline staff for assistance.
From the Emirates website