소켓통신에서 도메인으로 접속할경우 관련 질문입니다.

//헤더파일 include
    #include <stdio.h>
    #include <stdlib.h>
    #include <unistd.h>
    #include <errno.h>
    #include <string.h>
    #include <netdb.h>
    #include <sys/types.h>
    #include <netinet/in.h>
    #include <sys/socket.h>
    #include <errno.h>
 
//변수 선언
    #define PORT 8080 // the port client will be connecting to 
    #define MAXDATASIZE 100 // max number of bytes we can get at once
    #define HOSTNAME school.com
    .
    .
    .
    .
        struct hostent *he;
        struct sockaddr_in their_addr; // connector's address information 
 
        if (argc != 2) {
            fprintf(stderr,"usage: client hostname\n");
            exit(1);
        }
 
        if ((he=gethostbyname(argv[1])) == NULL) {  // get the host info 
            perror("gethostbyname");
            exit(1);
        }
 
        if ((sockfd = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
            perror("socket");
            exit(1);
        }
 
        their_addr.sin_family = AF_INET;    // host byte order 
        their_addr.sin_port = htons(PORT);  // short, network byte order 
        their_addr.sin_addr = *((struct in_addr *)he->h_addr);
       .
       .
       .
       .
       .