Hello! The icmp example provided with the asio-library throws a system error with code 10044 "The support for the specified socket type does not exist in this address family." when compiled with _WIN32_WINNT 0x0500 and executed on an Win2000 machine. The error comes from the gai_echeck()-function which is called with family AF_INET and socktype SOCK_RAW: inline int gai_echeck(const char* host, const char* service, int flags, int family, int socktype, int protocol) { .... switch (family) { case AF_UNSPEC: break; case AF_INET: case AF_INET6: if (socktype != 0 && socktype != SOCK_STREAM && socktype != SOCK_DGRAM) return EAI_SOCKTYPE; ... I have attached the callstack for call to gai_echeck() I'm using Visual Studio 2005 and boost 1.39. I changed the return value of gai_echeck() back to 0 in the debugger and then the rest of the icmp(ping) example ran without any apparent problems. Best regards, Wolfgang boost::asio::detail::socket_ops::gai_echeck(const char * host=0x0012fad0, const char * service=0x0012faa8, int flags=0, int family=2, int socktype=3, int protocol=1) Line 1380 C++ boost::asio::detail::socket_ops::getaddrinfo_emulation(const char * host=0x0012fad0, const char * service=0x0012faa8, const addrinfo * hintsp=0x0012fa78, addrinfo * * result=0x0012faf0) Line 1441 + 0x1d bytes C++ boost::asio::detail::socket_ops::WspiapiGetAddrInfo(const char * host=0x0012fad0, const char * service=0x0012faa8, const addrinfo * hints=0x0012fa78, addrinfo * * result=0x0012faf0, boost::system::error_code & ec={...}) Line 1801 + 0x15 bytes C++ boost::asio::detail::resolver_serviceboost::asio::ip::icmp::resolve(boost::shared_ptr<void> & __formal={...}, const boost::asio::ip::basic_resolver_queryboost::asio::ip::icmp & query={...}, boost::system::error_code & ec={...}) Line 147 + 0x51 bytes C++ boost::asio::ip::resolver_serviceboost::asio::ip::icmp::resolve(boost::shared_ptr<void> & impl={...}, const boost::asio::ip::basic_resolver_queryboost::asio::ip::icmp & query={...}, boost::system::error_code & ec={...}) Line 105 + 0x1b bytes C++ boost::asio::ip::basic_resolverboost::asio::ip::icmp >::resolve(const boost::asio::ip::basic_resolver_queryboost::asio::ip::icmp & q={...}) Line 98 + 0x1d bytes C++ pinger::pinger(boost::asio::io_service & io_service={...}, const char * destination=0x00324199) Line 32 + 0x1a bytes C++ main(int argc=2, char * * argv=0x00324170) Line 155 + 0x16 bytes C++