Reputations of domain registrars are calculated based on the hosting of risky domains. The more undesirable domains a registrar hosts, the lower is its reputation. The risk level of the hosted domains is also a factor in determining the reputation. When a user attempts to access a hosted domain, the calculated reputation of the hosting domain registrar is used in determining what security steps to apply to the access attempt. The worse the reputation of the hosting registrar, the more security is applied, all else being equal.