A policy service enforces network policy for clients and servers of a computer network. The servers are accessible to the clients by way of hostnames and network addresses. Hostnames are stored in association with network addresses and update information. The update information indicates a priority with which to update a particular network address of a particular host. Such updates can be made using forward domain name system (DNS) resolutions. A subset of the hosts is prioritized for update based on the update information. A predictive process can be used to define the prioritized subset of hosts. The network addresses of the prioritized subset of hosts can then be updated before other network addresses of other hosts are updated. The association of hostnames and network addresses can be converted into a routing table, which can be loaded onto a router of the network.