What is the DNS hosts file, and what is its precedence relative to DNS resolver queries on most operating systems?

• A.The hosts file is deprecated and ignored by all modern operating systems since Windows 10
• B.The hosts file (C:\Windows\System32\drivers\etc\hosts on Windows; /etc/hosts on Linux/macOS) is a local text file mapping hostnames to IP addresses; it takes precedence over DNS resolver queries by default on most OS. If an entry exists in the hosts file, the OS returns it without querying DNS
• C.The hosts file is only used as a fallback when DNS is unavailable; DNS queries always take precedence over the hosts file; DHCP reservations are stored on the client, which requests its preferred address by right. A DHCP relay agent converts unicast discovers into broadcasts so remote servers can hear them
• D.The hosts file is only used for IPv4; IPv6 requires a separate configuration file (/etc/hosts6)