NAME

       gai.conf - getaddrinfo(3) configuration file

DESCRIPTION

       A  call  to  getaddrinfo(3)  might  return  multiple answers.  According to RFC 3484 these
       answers must be sorted so that the answer with the highest success rate is  first  in  the
       list.   The  RFC  provides  an algorithm for the sorting.  The static rules are not always
       adequate, though.  For this reason, the  RFC  also  requires  that  system  administrators
       should   have   the  possibility  to  dynamically  change  the  sorting.   For  the  glibc
       implementation, this can be achieved with the /etc/gai.conf file.

       Each line in the configuration file consists of  a  keyword  and  its  parameters.   White
       spaces in any place are ignored.  Lines starting with '#' are comments and are ignored.

       The keywords currently recognized are:

       label netmask precedence
              The  value  is added to the label table used in the RFC 3484 sorting.  If any label
              definition is present in the configuration file, the default  table  is  not  used.
              All  the  label definitions of the default table which are to be maintained have to
              be duplicated.  Following the keyword, the line has to contain a network mask and a
              precedence value.

       precedence netmask precedence
              This  keyword is similar to label, but instead the value is added to the precedence
              table as specified in RFC 3484.  Once again, the presence of  a  single  precedence
              line in the configuration file causes the default table to not be used.

       reload <yes|no>
              This  keyword  controls whether a process checks whether the configuration file has
              been changed since the last time it was read.  If the value is "yes", the  file  is
              reread.  This might cause problems in multithreaded applications and is generally a
              bad idea.  The default is "no".

       scopev4 mask value
              Add another rule to the RFC 3484 scope table for IPv4  address.   By  default,  the
              scope  IDs  described in section 3.2 in RFC 3438 are used.  Changing these defaults
              should hardly ever be necessary.

FILES

       /etc/gai.conf

VERSIONS

       The gai.conf file is supported since glibc 2.5.

EXAMPLES

       The  default  table  according  to  RFC 3484  would  be  specified  with   the   following
       configuration file:

           label  ::1/128       0
           label  ::/0          1
           label  2002::/16     2
           label ::/96          3
           label ::ffff:0:0/96  4
           precedence  ::1/128       50
           precedence  ::/0          40
           precedence  2002::/16     30
           precedence ::/96          20
           precedence ::ffff:0:0/96  10

SEE ALSO

       getaddrinfo(3), RFC 3484