On Linux with glibc, static linking breaks DNS resolver client: gethostbyname(3) and friends. As a workaround, you can link to musl libc, but that is only for software written in C, it does not work with C++. FreeBSD is better in this regard (their libc allows static linking without breaking DNS client, even for C++ software). However, on both OSes static linking is incompatible with dlopen(3) and dlsym(3), i.e. your application will be unable to load any .so files, so you if you link statically to libc then you must statically link to every other library. This is unlike Windows, where OS kernel API DLLs (ntdll.dll, kernel32.dll) are separated from libc DLL (msvcrt.dll if MSVC, cw3220.dll if Borland C++, mingw-something-something.dll if MinGW, IIRC there was something similar for Watcom etc), so libcs from different compilers may load simultaneously to the address space of a process (e.g. in application with third party plugins compiled against different libc, or a different version of the same vendor libc). Also on Windows OS kernel API DLLs (ntdll.dll, kernel32.dll) are always loaded to the address space of your process, even if you link to libc statically. So your application always can call LoadLibrary(), TlsAlloc() etc, and it is possible to write libc-less applications in the plain C.