（七）gethostbyname函数

参考:
学习笔记之gethostbyname函数

1. gethostbyname函数

#include <netdb.h>
#include <arpa/inet.h>

#include <iostream>
using namespace std;

int main()
{
    struct hostent *hptr;
    char szIP[64];
    hptr = gethostbyname("www.baidu.com");
    if(hptr == nullptr){
        cout<<"gethostbyname error"<<endl;
    }
    cout<<"official hostname: "<<hptr->h_name<<endl;
    for(char** pptr=hptr->h_aliases; *pptr!=nullptr; pptr++){
        cout<<"  alias: "<<*pptr<<endl;
    }
    if(hptr->h_addrtype == AF_INET){
        cout<<"ipv4"<<endl;
        for(char** pptr=hptr->h_addr_list; *pptr!=nullptr; pptr++){
            //cout<<"ip: "<<*pptr<<endl;
            cout<<"ip: "<<inet_ntop(hptr->h_addrtype, *pptr, szIP, sizeof(szIP))<<endl;
        }
    }
    
    return 0;
}

2. 结果

ld@ld-pc:~/workspace$ ./gethostbyname_demo 
official hostname: www.a.shifen.com
  alias: www.baidu.com
ipv4
ip: 183.232.231.172
ip: 183.232.231.173

3. nslookup命令

nslookup - query Internet name servers interactively

ld@ld-pc:~/workspace$ nslookup www.baidu.com
Server:		127.0.1.1
Address:	127.0.1.1#53

Non-authoritative answer:
www.baidu.com	canonical name = www.a.shifen.com.
Name:	www.a.shifen.com
Address: 183.232.231.172
Name:	www.a.shifen.com
Address: 183.232.231.173