NPM- 6th ex

6th ex:-

PROGRAM:

#include<netdb.h>

#include<sys/socket.h>

int main()

{

 char hname[50],ptr[40],**pptr,*ptr1,ipadd[40];

 char str[128];

 struct hostent *hptr,*dptr;

 size_t l;

 struct in_addr sa;

 int ch;

 while(ch!=4)

 {

  printf("Select one DNS operation\n");

  printf("1.Get-Host-Name\n");

  printf("2.Get-Host-by-Name\n");

  printf("3.Get-Host-by-Address\n");

  printf("4.Exit\n");

  printf("Enter your choice :  ");

  scanf("%d",&ch);

  switch(ch)

  {

   case 1:

    gethostname(hname,l);

    printf("Host name: %s\n",hname);

   break;

   case 2:

    printf("Enter the host name :  ");

    scanf("%s",ptr);

    if((hptr=gethostbyname(ptr))==NULL)

    perror("Error");

    printf("Official Name : %s\n",hptr->h_name);

    printf("Type %d\n",hptr->h_addrtype);

    pptr=hptr->h_addr_list;

    for(pptr;*pptr!=NULL;*pptr++)

    printf("Address : %s\n",inet_ntop(hptr->h_addrtype,*pptr,str,sizeof(str)));

    for(pptr=hptr->h_aliases;*pptr!=NULL;*pptr++)

    printf("the name is %s \n",*pptr);

   break;

   case 3:

    printf("Enter the IP address :  ");

    scanf("%s",ipadd);

    inet_pton(AF_INET,ipadd,&sa.s_addr);

    dptr=gethostbyaddr(&sa.s_addr,4,AF_INET);

    printf("Host Name : %s\n",dptr->h_name);

   break;

   case 4:

   exit(0);

  }

 }

}

OUTPUT:

[it86091@vecit ~]$ cc program6.c

[it86091@vecit ~]$ ./a.out

Select one DNS operation

1.Get-Host-Name

2.Get-Host-by-Name

3.Get-Host-by-Address

4.Exit

Enter your choice :  1

Host name: vecit

Select one DNS operation

1.Get-Host-Name

2.Get-Host-by-Name

3.Get-Host-by-Address

4.Exit

Enter your choice :  2

Enter the host name :  vecit

Official Name : vecit

Type 2

Address : 127.0.0.1

the name is localhost.localdomain

the name is localhost

Select one DNS operation

1.Get-Host-Name

2.Get-Host-by-Name

3.Get-Host-by-Address

4.Exit

Enter your choice :  3

Enter the IP address :  127.0.0.1

Host Name : vecit

Select one DNS operation

1.Get-Host-Name

2.Get-Host-by-Name

3.Get-Host-by-Address

4.Exit

Enter your choice :  4

[it86091@vecit ~]$