Generally described, the present disclosure is directed to managing request routing functionality corresponding to resource requests for one or more resources associated with a content provider. A service provider can assign a set of DNS servers corresponding to a distributed set of network addresses, or portions of network addresses, for one or more identifiable domains. If the service provider receives requests to assign a DNS server to conflicting domains, the set of DNS servers for each identifiable domain are assigned such that there are no matching network addresses between the sets of domains associated with the conflicting domains. Thereafter, DNS resolver components can be configured such that DNS queries may be resolved in accordance with a determination of an authoritative DNS server based on the identified destination address associated with the DNS queries.