Methods, systems and computer readable media for user authentication for proxy-configured clients in captive portal deployments are described. In some implementations, the method can include receiving, at a captive portal, a request from a client device to resolve a proxy IP address, and determining whether the client device has been authenticated. The method can also include, when the client device has not been authenticated, causing the captive portal to act as an intermediate domain name system (DNS) server and forwarding the DNS request to one or more other DNS servers, and evaluating any received responses from the one or more other DNS servers. The method can include, when received responses contain an IP address, replying to the client with the received IP address, and when the received responses do not contain an IP address, replying to the client with an IP address of the captive portal.