res_close()--Close Socket and Reset _res Structure

 #include <sys/types.h>
 #include <netinet/in.h>
 #include <arpa/nameser.h>
 #include <resolv.h>

 void res_close(void)

The res_close() function is used to reset the _res structure to the beginning defaults and close a socket that is opened as a result of the RES_STAYOPEN flag.

Authorities:

No authorization is required.

Return Value

None

Usage Notes

1. If res_send() was previously called with RES_STAYOPEN set in the options field of the _res structure, res_close() closes the socket that was left open. res_close() does not attempt the close if there was no socket left open.
   
   
2. res_close() sets the _res structure to default values.
   
   • The retrans field is set to 5.
   • The retry field is set to 4.
   • The options field has the RES_RECURSE, RES_DEFDNAMES, and RES_DNSSRCH bits set.
   • The nscount field is set to 1.
   • All other fields in the _res structure are cleared.
   • In a thread-enabled environment _res structure is shared among all threads within a process.

Related Information

• res_nclose()--Close Socket and Reset res Structure
  
  
• res_hostalias()--Retrieve the host alias
  
  
• res_init()--Initialize _res Structure
  
  
• res_mkquery()--Place Domain Query in Buffer
  
  
• res_query()--Send Domain Query
  
  
• res_search()--Search for Domain Name
  
  
• res_send()--Send Buffered Domain Query
  
  
• res_xlate()--Translate DNS Packets