
Using RES_USE_INET6 is deprecated and has been removed by glibc 2.30[1]. Instead, there's now a function `gethostbyname2(3)` which takes the address family as second argument to force IPv6 resolution[2]. [1] https://sourceware.org/ml/libc-alpha/2019-08/msg00029.html [2] https://linux.die.net/man/3/gethostbyname2