Measures, including methods, systems and non-transitory computer-readable storage mediums, for providing a Domain Name Service (DNS) configuration service for one or more network services provided in a cloud environment. Update data relating to one or more relationship updates that have occurred in at least one of the one or more network services is received. The one or more relationship updates relate to one or more service provision units in a cluster of service provision units deployed in the cloud environment to provide the at least one network service. DNS policy configuration data associated with the at least one network service is identified. On the basis of the identified DNS policy configuration data, data in a DNS configuration data database is updated.