TLD refers to the highest level in the ___ name hierarchy.

The correct answer is domain. TLD, or Top-Level Domain, represents the highest level in the domain name hierarchy that is used within the Domain Name System (DNS). A domain name consists of several components, where the TLD is the part that comes after the last dot in a full domain name, such as ".com," ".org," or ".net."

Understanding the structure of domain names is crucial for navigating the internet efficiently. The hierarchy starts with the TLD at the top, followed by the second-level domain (which typically represents the organization or entity), and can include further subdivisions. Other options like IP, URL, and subdomain refer to different components related to networking and web structures but do not pertain directly to the highest level of the domain name hierarchy.