There are several options for free DNS server software that you can use to set up your own DNS server. Here are some popular choices:
BIND:
BIND (Berkeley Internet Name Domain) is the most widely used DNS server software on the Internet. It is an open-source software that is developed and maintained by the Internet Systems Consortium (ISC).
BIND is available for free and is supported on multiple platforms, including Linux, Unix, and Windows.
MaraDNS:
MaraDNS is a lightweight, open-source DNS server that is designed to be easy to set up and maintain. It is written in the C programming language and is available for free on multiple platforms, including Linux, Unix, and Windows.
PowerDNS:
PowerDNS is a high-performance, open-source DNS server that is designed to handle large volumes of DNS traffic. It supports multiple database backends and is available for free on multiple platforms, including Linux, Unix, and Windows.
Unbound:
Unbound is a flexible, open-source DNS server that is designed to be fast and secure. It is written in the C programming language and is available for free on multiple platforms, including Linux, Unix, and Windows.