Address Lookup

Address lookup is done using the resolver library (-lresolv on the link command). The system's config determines which protocol is used to perform the actual lookup (NIS, DNS, /etc/hosts, etc.). Here is a code snippet:

/* Description of data base entry for a single host.  */
struct hostent
{
  char *h_name;        /* Official name of host.              */
  char **h_aliases;    /* Alias list.                         */
  int h_addrtype;      /* Host address type.                  */
  int h_length;        /* Length of address.                  */
  char **h_addr_list;  /* List of addresses from name server. */
};