研究了一下：看host.conf的手冊可以看到說明：

multi ： Valid values are on and off. If set to on, the resolver library will return all valid addresses for a host that appears in the /etc/hosts ly stead of ault on defthr. , as it may cause a substantial performance loss at sites with large hosts files.

the resolver library 不是ping， ping只會取get的第一條，可以個通過：

getent hosts a

來取得hosts設定中的有效設定,getent指令用來取得重要設定檔的內容，
getnet hosts其實最後是透過呼叫gethostbyname系統api函式來進行解析的，所以可以透過在程式碼中呼叫gethostbyname來取得server name所對應的所以ip，下面是隨便找的一段程式碼：

#include <iostream>
#include <typeinfo>

#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <stdio.h>

int main(int argc, char **argv)
{
    char   *ptr, **pptr;
    struct hostent *hptr;
    char   str[32];
    ptr = argv[1];

    if((hptr = gethostbyname(ptr)) == NULL)
    {
        printf(" gethostbyname error for host:%s\n", ptr);
        return 0;
    }

    printf("official hostname:%s\n",hptr->h_name);
    for(pptr = hptr->h_aliases; *pptr != NULL; pptr++)
        printf(" alias:%s\n",*pptr);

    switch(hptr->h_addrtype)
    {
        case AF_INET:
        case AF_INET6:
            pptr=hptr->h_addr_list;
            for(; *pptr!=NULL; pptr++)
                printf(" address:%s\n",
                       inet_ntop(hptr->h_addrtype, *pptr, str, sizeof(str)));
            printf(" first address: %s\n",
                       inet_ntop(hptr->h_addrtype, hptr->h_addr, str, sizeof(str)));
        break;
        default:
            printf("unknown address type\n");
        break;
    }

    return 0;
}

執行結果：

$./a.out a
official hostname:a
 address:187.0.0.3
 address:127.0.0.1
 address:127.0.0.2
 first address: 187.0.0.3