[jwilk]

The author is confused. glibc does support IDN, but of course it's not enabled by default. The applications that want IDN have to opt in by specifying an appropriate flag.

http://man7.org/linux/man-pages/man3/getaddrinfo.3.html (search for "Internationalized Domain Names")

[CaliforniaKarl]

It looks like getaddrinfo does have that ability, but I could not tell if gethostbyname supports it.

[aaronmdjones]

Please stop using gethostbyname(3). Among other things, it doesn't support IPv6.

[jwilk]

gethostbyname() is obsolete. And no, it doesn't support IDN.