.SD is the Internet country code top-level domain (ccTLD) for Sudan according to ISO 3166 List. It continues in use in South Sudan until the .ss TLD becomes operational.

Sudan Internet Society (SIS) manages the Domain Name Registration under Sudan Top Level Domain .sd.

SIS is a non-Governmental, Technical and Professional Organization.

At the time of the initial submission of the Domain Name request, and at all material times thereafter, it shall have an operational name service from at least two operational Internet servers for that domain name. Each server is and will continue to be fully connected to the Internet and capable of receiving queries under that Domain Name and responding thereto.