Below here follows defines for the CURLOPT_IPRESOLVE option. If a host name resolves addresses using more than one IP protocol version, this option might be handy to force libcurl to use a specific IP version.
default, resolves addresses to all IP versions that your system allows
resolve to ipv4 addresses
resolve to ipv6 addresses
See Implementation
Below here follows defines for the CURLOPT_IPRESOLVE option. If a host name resolves addresses using more than one IP protocol version, this option might be handy to force libcurl to use a specific IP version.