Configuring a Dynamic API

There are three ways to specify user-provided, dynamically loading resolver routines. You can use the NSORDER environment variable, the /etc/netsvc.conf configuration file, or the /etc/irs.conf configuration file.

With any of these sources, you are not restricted in the number of options that you can enter, nor in the sequence in which they are entered. You are, however, restricted to a maximum number of 16 user modules that a user can specify from any of these sources.

The NSORDER environemnt variable is given the highest priority. Next is the /etc/netsvc.conf configuration file, then the /etc/irs.conf configuration file. A user option specified in a higher priority source (for example, NSORDER) causes any user options specified in the lower priority sources to be ignored.

NSORDER Environment Variable

You can specify zero or more user options in the environment variable NSORDER. For example, on the command line, you can type:

 export NSORDER=local, bind, bob, nis, david4, jason6

In this example, the operating system invokes the listed name resolution modules, left to right, until the name is resolved. The modules named local, bind, and nis are reserved by the operating system, but bob, david4, and jason6 are user-provided modules.

/etc/netsvc.conf Configuration File

You can specify zero or more user options in the configuration file /etc/netsvc.conf. For example:

  hosts=nis, jason4, david, local, bob6, bind

/etc/irs.conf Configuration File

You can specify zero or more user options in the configuration file /etc/irs.conf. For example:

  hosts dns continue
  hosts jason6 merge
  hosts david4