Help with gethostbyname

[en_7123]

Here's a simple program that uses gethostbyname

#include<stdio.h>
#include<stdlib.h>
#include<sys/socket.h>
#include<sys/types.h>
#include<netinet/in.h>
#include<error.h>
#include<strings.h>
#include<unistd.h>
#include<arpa/inet.h>
#include<netdb.h>         //struct hostent

int main()

{
char s[INET_ADDRSTRLEN];    //Buffer to store the ip
char **ptr;                  
char str[100];       //Name of host on which lookup has to be performed
struct hostent *hptr;                   
printf("Enter the string :");//Enter the name of host
gets(str);
printf("\n");
if((hptr=gethostbyname(str))==NULL) //Get host information
{
printf("Error in host name :");      //Error message 
exit(1);
}
printf("host officail name %s",hptr->h_name); //Print host officail name
printf("\n\n\n");
for(ptr=hptr->h_aliases;*ptr!=NULL;ptr++)
{
printf("Aliases : %s\n",*ptr); //Print Alias name of the host
}
printf("\n");
for(ptr=hptr->h_addr_list;*ptr!=NULL;ptr++)  //Print all ip address use by host
{
printf("Adress list %s\n",inet_ntop(AF_INET,ptr,s,sizeof(s)));
}



}

I just want to know why the result differ when I give nameofanysite.com as input and "xxx.nameofsite.com" as input . Also every time I run it even though giving the same site as input i get a list of different IP address list.Why is so.
thanx
Note .Please READ XXX AS www

[rcgreen]

Well, as a general concept, site dot com is a top level domain,
while www dot site dot com literally means host www
at site dot com. So www is not part of the http:
protocol prefix, but is a hostname, traditionally used for web servers.
site dot com is just the domain, with no host specified.