DNSO is the abbreviation for the Domain Name Supporting Organization, one of the three ICANN supporting organizations called for under the ICANN by-laws. It has now been succeeded by the Generic Names Supporting Organization (GNSO). The DNSO advised the ICANN Board about handling issues related to the Domain Name System (DNS). Its primary agenda was to discuss how and when to expand the Internet by adding new TLDs beyond .com.
The DNSO was comprised of two bodies: the Names Council (NC), which was made up of elected representatives from the DNSO Constituencies, and the General Assembly (GA), made up of all interested entities and individuals.
The initial constituencies of the DNSO were as follows:
- ccTLD Registries
- gTLD Registries
- Commercial and Business entities
- Non-Commercial Domain Name Holders
- Internet Service Providers (ISPs) and Connectivity Providers
- Registrars 
- The DNSO serves in an advisory role to the ICANN Board and provides the Board with substantive policies related to the DNS.
- The recommendations provided to the ICANN Board by the DNSO first needed to build a consensus before being submitted to the Board.
- All the recommendations made by the DNSO to the Board are made open to all Supporting Organizations (SOs) so that they can comment.
The ICANN Board accepts the recommendations of the DNSO only if it thinks that:
- The policy is in the interest of the Corporation and helps to further the purposes of the Corporation
- The policy is consistent with the Articles and Bylaws of the Corporation
- The policy was framed through an open and fair process
- The policy is not opposed by other Supporting Organizations
- The Board would not adopt any recommendation by the DNSO unless the votes, excluding those of the DNSO-selected Directors, are in favor of adoption by the Board
- If the Board is not satisfied with a recommendation then it can return it to the DNSO for further consideration, citing the reasons for its declination. If the DNSO still fails to make the policy acceptable, then the ICANN Board may initiate, modify or amend and then approve the recommendation.
Current situation of the DNSO
Starting in 2003, the responsibilities of the DNSO were undertaken by the Generic Names Supporting Organization (GNSO).