Various techniques for providing defense against NXDOMAIN hijacking in domain name systems are disclosed herein. In one embodiment, a method includes receiving a user input from a user to a search box in an application executing on a computing device connected to the Internet via a facility provided by an internal service provider (“ISP”) and resolving the received user input to the search box as a DNS query without using a caching server provided by the ISP. The method can then include determining whether the DNS query causes an NXDOMAIN condition and in response to determining that the DNS query causes an NXDOMAIN condition, indicating that the received user input does not have a corresponding IP address in the domain name system.