一个域名对应多个 IP

我想问2个问题，在提问前，我先进行下说明。
在Linux下编译(gcc -o hostinfo hostinfo.c)下面的代码后

#include<stdio.h>
#include<netdb.h>
#include<arpa/inet.h>
#include<netinet/in.h>

int main(int argc, char **argv)
{
    if(argc != 2){
         fprintf(stderr, "usage: %s <domain name or dotted-decimal>\n", argv[0]);
         return 0;
    }

   char **pp;
   struct in_addr addr;
   struct hostent *hostp;

   if(inet_aton(argv[1], &addr) != 0){
       hostp = gethostbyaddr((const char *)&addr, sizeof(addr), AF_INET);
   }else{
       hostp = gethostbyname(argv[1]);
   }

   printf("official hostname: %s\n", hostp->h_name);

   for(pp = hostp->h_aliases; *pp != NULL; pp++){
        printf("alias: %s\n", *pp);
   }

   for(pp = hostp->h_addr_list; *pp != NULL; pp++){
        addr.s_addr = ((struct in_addr *) *pp)->s_addr;
        printf("address: %s\n", inet_ntoa(addr));
   }

   return 0;
}
运行命令:

>./hostinfo www.17173.com
>./hostinfo www.17173.com
得到结果如下:

official hostname: poolct.17173.com
alias: www.17173.com
alias: pooldist.17173.com
address: 117.27.230.84
address: 117.27.230.82
address: 117.27.230.83
address: 117.27.230.98
address: 117.27.230.75
address: 117.27.230.86
address: 117.27.230.85
address: 117.27.230.80
address: 117.27.230.99  

official hostname: poolct.17173.com
alias: www.17173.com
alias: pooldist.17173.com
address: 117.27.230.83
address: 117.27.230.82
address: 117.27.230.84
address: 117.27.230.96
address: 117.27.230.75
address: 117.27.230.88
address: 117.27.230.85
address: 117.27.230.80
address: 117.27.230.99

现在我想请问2个问题：
A.为什么每次返回的 ip 地址的顺序不一样？
B.这种顺序有何作用?