h_errno

Host error variable

Synopsis:

#include <netdb.h>

extern int h_errno;

Library:

libsocket

Description:

The h_errno variable can be set by any one of the following functions:

• gethostbyaddr()
• gethostbyaddr_r()
• gethostbyname()
• gethostbyname_r()
• res_query()
• res_search()

It can be set to any one of the following:

HOST_NOT_FOUND

Authoritative answer: Unknown host.

NO_DATA

Valid name, no data record of the requested type. The name is known to the name server, but has no IP address associated with it -- this isn't a temporary error. Another type of request to the name server using this domain name will result in an answer (e.g. a mail-forwarder may be registered for this domain).

NO_RECOVERY

Unknown server error. An unexpected server failure was encountered. This is a nonrecoverable network error.

TRY_AGAIN

Nonauthoritative answer: Host name lookup failure. This is usually a temporary error and means that the local server didn't receive a response from an authoritative server. A retry at some later time may succeed.

Classification:

Unix

Caveats:

Unlike errno, h_errno isn't thread-safe.

See also:

errno, gethostbyaddr(), gethostbyaddr_r(), gethostbyname(), gethostbyname_r(), res_query(), res_search()