实现IP到域名的转换
function GetDomainName(Ip:string):string;
var
pHHostent;
data:twsadata;
ii:dword;
begin
WSAStartup($101, Data);
ii:=inet_addr(pchar(ip));
pH:=gethostbyaddr(@ii,sizeof(ii),PF_INET);
if (ph<>nil) then
result:=pH.h_name
else
result:='';
WSACleanup;
end;