Which network service resolves user-friendly names to numerical IP addresses?

The correct answer is DNS, which stands for Domain Name System. This service is essential for resolving user-friendly domain names, like www.example.com, into their corresponding numerical IP addresses, such as 192.0.2.1. When a user types a website's name into their browser, the DNS translates that name into an IP address that the computer can use to locate the server hosting the website. This process allows users to access resources on the internet without needing to remember complex numerical addresses, simplifying navigation and enhancing the usability of the web.

The other options play different roles in network functionality. DHCP, or Dynamic Host Configuration Protocol, is responsible for automatically assigning IP addresses and other network configuration settings to devices on a network. SMTP, or Simple Mail Transfer Protocol, is used for sending emails between servers, while FTP, or File Transfer Protocol, facilitates the transfer of files over the internet. Each of these services is important in its own context, but they do not perform the specific function of name resolution that DNS provides.