Source: As worded by Indian Railways, Government of India

Yes, you can. In fact, you can book your ticket for any train on the Indian Railways network, from any originating station to any destination* at any of the 2926 Computerized Reservation Centers, across the country. With the network of New Delhi, Mumbai, Kolkata, Secunderabad and Chennai Passenger Reservation Systems, you can now book your onward and return journey tickets from any Computerised Reservation Centre nearest to you - not just from major railway stations. This networking makes reservation of tickets faster and simpler.

Reserved tickets can also be obtained by accessing the website www.irctc.co.in . Payments can be made directly through the website. Please follow the instructions posted on the website and on Page 301

*Reservations can be made subject to distance restrictions and availability of quotas