A walled garden system includes a firewall controlling access between a first network and a second network at least by allowing connection requests originating from a user device on the first network to a destination IP address on the second network in response to determining that the destination IP address matches a cleared IP address on a cleared IP addresses list. A controller receives a domain name service (DNS) reply from a DNS server on the second network, and determines whether a domain name specified within the DNS reply matches a cleared domain name on a cleared domain names list. In response to determining that the domain name specified within the DNS reply matches the cleared domain name on the cleared domain names list, the controller adds a resolved IP address specified in the DNS reply to the cleared IP addresses list as a new cleared IP address.