First, second, and third sets of addresses are created. The first set includes addresses registered in a name server; both the second and third sets include addresses not registered in the name server and that are disjoint. A first address of a first server that has failed and to which access is to be prohibited is moved from the first to the third set, is removed from the first server, assigned to a second server, and removed from the name server. Usage parameter values of the first address are monitored to determine whether at least one is below a value. If so, the first address is removed from the second server and moved from the third to the second set. Upon access to the first server no longer being prohibited, a second address of the second set is assigned to the first server and added to the name server.