Building Binaries for Linux , GLIBC help

So Im trying to build some binaries for as most linux systems as possible. I use the functions gethostbyname () which is defined in glibc, I also link against libcurl which is also using this function.

When I attemped to build a static binary I received a number of warning telling me wherever gethostbyname( ) was used, that this binary must have the same version of GLIBC that I linked against (2.3).

I guess there really no getting around this if I want to use that function. So I guess my question is how do I compile against earlier version of GLIBC? Also is there an easy way for me to determine what version of GLIBC is on other linux machines?