Abstract: A facility comprising systems and methods for preventing or protecting against the registration of domain names that exactly match, contain, or are similar to a mark is provided. The facility maintains a data structure for recording strings that an entity, such as an individual, company, or other organization, has an interest in protecting, such as a domain name that exactly matches, contains, or is similar to a mark owned or held by the entity. In response to requests to register a domain name that includes a recorded string, the facility can prevent registration of that domain name even if the domain name is not registered. The facility may periodically share or publish the data structure with any number of domain name registrars or registries. In this manner, a mark holder can prevent or protect against registration of domain names under any number of top-level domains with a single request.