flags may be passed by bitwise `OR`ing their values.

* `all` {boolean} When `true`, the callback returns all resolved addresses in

an array. Otherwise, returns a single address. **Default:** `false`.

unsorted. When `ipv4first`, the resolved addresses are sorted by placing

IPv4 addresses before IPv6 addresses. When `ipv6first`, the resolved

addresses are sorted by placing IPv6 addresses before IPv4 addresses.