One important problem when deploying interdomain path selection is advertising metrics that hold for a long period of time. In this paper we propose a method to aid interdomain path selection mechanisms in that sense. We present a means of computing a bound on the end-to-end delay of traversing a domain considering that the traffic varies within a given uncertainty set. This provides a robust and a verifiable quality of service value for traversing the autonomous system (AS), without revealing confidential information. Consequently, the bound can be safely conceived as a metric to be announced by each AS in the process of interdomain path selection. We show how the maximum delay value is obtained for an interdomain bandwidth demand and we propose an exact method and a numerical approximation method for computing it, neither of which rely on a complex monitoring infrastructure. Simulations with real data that illustrate the problem and validate our results are also presented.