I was just about trying out asio on Windows. I compiled as described, and tried to run the checks as: nmake -f Makefile.msc check and received: INFO: deadline_timer_test started INFO: deadline_timer_test ended with exit code 0 INFO: demuxer_test started INFO: demuxer_test ended with exit code 0 INFO: datagram_socket_test started INFO: datagram_socket_test ended with exit code 0 INFO: error_handler_test started INFO: error_handler_test ended with exit code 0 INFO: fixed_buffer_test started INFO: fixed_buffer_test ended with exit code 0 INFO: ipv4_host_resolver_test started FAIL: tests\unit\ipv4_host_resolver_test.cpp(88):test_if_hosts_equivalent(h1, h3) FAIL: tests\unit\ipv4_host_resolver_test.cpp(106):test_if_hosts_equivalent(h1, h7) INFO: ipv4_host_resolver_test ended with exit code 1 Is there anything I am missing? Or is this a known issue? Regards, Roland