The goal of this research is to explore the nature of the response relation in online learning networks. We ask whether actors choose their response partners at random or whether certain special mechanisms are at work. We compare the observed values of clustering of responses in 95 online learning networks with the predictions of two suitable Random Graph models. All the online distance learning networks exhibit clustering that is incompatible with the random choices of response partners, with no constraints on the response capacities of actors. But the observed clustering in all networks is compatible with the random choices of response partners subject to constraints on their total response capacities. We provide a possible explanation for this behavior, based on the nature and goal of the online learning networks, and discuss the practical implications for online distance education.