A NULL -terminated array of alternate names for the host.
The type of address being returned; usually AF_INET.
The length, in bytes, of the address.
A NULL -terminated array of network addresses for the host. Host addresses are returned in network byte order.
The first address in h_addr_list; this is for backward compatibility.
When using the nameserver, gethostbyname and gethostbyname2 will search for the named host in the current domain and its parents unless the name ends in a dot. If the name contains no dot, and if the environment variable "HOSTALIASES" contains the name of an alias file, the alias file will first be searched for an alias matching the input name. See hostname(7) for the domain search procedure and the alias file format.
The gethostbyname2 function is an evolution of gethostbyname which is intended to allow lookups in address families other than AF_INET, for example AF_INET6.
The sethostent function may be used to request the use of a connected TCP socket for queries. If the stayopen flag is non-zero, this sets the option to send all queries to the name server using TCP and to retain the connection after each call to gethostbyname, gethostbyname2 or gethostbyaddr. Otherwise, queries are performed using UDP datagrams.
The endhostent function closes the TCP connection.
The herror function writes a message to the diagnostic output consisting of the string argument string, the constant string "": "", and a message corresponding to the value of h_errno.
The hstrerror function returns a string which is the message text corresponding to the value of the err argument.
This is usually a temporary error and means that the local server did not receive a response from an authoritative server. A retry at some later time may succeed.
Some unexpected server failure was encountered. This is a non-recoverable error.
The requested name is valid but does not have an IP address; this is not a temporary error. This means that the name is known to the name server but there is no address associated with this name. Another type of request to the name server using this domain name will result in an answer; for example, a mail-forwarder may be registered for this domain.