gethostbyname: Unknown server error when resolving hostnames with underscore

[Krzysztof Klimonda]

This small snippet of code returns "gethostbyname: Unknown server error" when called under 14.04 and 16.04:

-----8<--------
#include <stdio.h>
#include <netdb.h>

int main(int argc, char *argv[])
{
    struct hostent *lh = gethostbyname("_http._tcp.nova.clouds.archive.ubuntu.com");

    if (lh)
        puts(lh->h_name);
    else
        herror("gethostbyname");
}
-----8<--------

While I have a feeling this hostname is not valid, that's what apt is trying to resolve after SRV query fails. The same code seems to be working in 16.10.