如何查询服务器并获取MX,A,NS记录

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <netinet/in.h>
#include <resolv.h>
#include <netdb.h>

#define N 4096

int main (int argc,char *argv[])
{
    u_char nsbuf[N];
    char dispbuf[N];
    ns_msg msg;
    ns_rr rr;
    int i,l;

    if (argc < 2) {
        printf ("Usage: %s <domain>n",argv[0]);
        exit (1);
    }

    // HEADER
    printf("Domain : %sn",argv[1]);
    // ------

    // A RECORD
    printf("A records : n");
    l = res_query(argv[1],ns_c_any,ns_t_a,nsbuf,sizeof(nsbuf));
    if (l < 0)
    {
      perror(argv[1]);
    }
    ns_initparse(nsbuf,l,&msg);
    l = ns_msg_count(msg,ns_s_an);
    for (i = 0; i < l; i++)
    {
      ns_parserr(&msg,ns_s_an,&rr);
      ns_sprintrr(&msg,&rr,NULL,dispbuf,sizeof(dispbuf));
      printf("t%s n",dispbuf);
    }
    //------------


    // MX RECORD
    printf("MX records : n");
    l = res_query(argv[1],ns_t_mx,sizeof(nsbuf));
    if (l < 0)
    {
      perror(argv[1]);
    }
    else
    {
#ifdef USE_PQUERY
      /* this will give lots of detailed info on the request and reply */
      res_pquery(&_res,stdout);
#else
      /* just grab the MX answer info */
      ns_initparse(nsbuf,&msg);
      l = ns_msg_count(msg,ns_s_an);
      for (i = 0; i < l; i++)
      {
        ns_parserr(&msg,i,&rr);
        ns_sprintrr(&msg,sizeof(dispbuf));
        printf ("t%sn",dispbuf);
      }
#endif
    }
    // ---------

    // NS RECORD
    printf("NS records : n");
    l = res_query(argv[1],ns_t_ns,dispbuf);
    }
    // ---------
    return 0;
}

根据要求收到很多相同的,即相同的A记录.与NS记录相同.我究竟做错了什么？
示例：

Domain : mail.ru
A records :
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
        mail.ru.                22S IN A        94.100.191.207
MX records :
        mail.ru.                1m57s IN MX     10 mxs.mail.ru.
NS records :
        mail.ru.                1m50s IN NS     ns.mail.ru.
        mail.ru.                1m50s IN NS     ns.mail.ru.
        mail.ru.                1m50s IN NS     ns.mail.ru.
        mail.ru.                1m50s IN NS     ns.mail.ru.
        mail.ru.                1m50s IN NS     ns.mail.ru.
        mail.ru.                1m50s IN NS     ns.mail.ru.

请帮忙.