Which of the following is a computer file used in an operating system to map hostnames to IP addresses?

The LMHOSTS file maps NetBIOS computer names to IP addresses for legacy Windows networking and is distinct from the general-purpose hostname resolution that the HOSTS file provides.

NSCD.CONF is the configuration file for the Name Service Cache Daemon, which caches name service lookup results for performance, but does not itself store or define hostname-to-IP mappings.

TMPFS is a volatile, RAM-backed temporary filesystem used by operating systems for ephemeral storage and has no relationship to hostname or IP address resolution.

The HOSTS file (located at /etc/hosts on Unix-like systems and C:\Windows\System32\drivers\etc\hosts on Windows) is a plain-text file the OS reads before querying DNS to resolve a hostname to an IP address. It provides a local, static hostname-to-IP mapping that takes precedence over DNS in most default OS configurations, making it the direct answer to this question.