The letter C used to be operated by the now defunct PSInet. What happened?
PSINet kept operating C with help from some other root name server operators. In April 2002, the major U.S. assets of PSINet were acquired by Cogent Communications. Those assets included the customer base and all the equipment supporting the network, including the existing C root server. Cogent took over the responsibility of operating C and has since augmented the C root server system.
