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Delay-tolerant networks (DTNs) are characterized by a possible absence of end-to-end communication routes at any instant. Yet, connectivity can be achieved over time and space, leading to evaluate a given route both in terms of topological length or temporal length. The problem of measuring temporal distances in a social network was recently addressed through postprocessing contact traces like email data sets, in which all contacts are punctual in time (i.e., they have no duration). We focus on the distributed version of this problem and address the more general case that contacts can have arbitrary durations (i.e., be nonpunctual). Precisely, we ask whether each node in a network can track in real time how "out-of-dateâ it is with respect to every other. Although relatively straightforward with punctual contacts, this problem is substantially more complex with arbitrarily long contacts: consecutive hops of an optimal …