IPv4-unique search order for sitename information

The resolver uses the IPv4-unique search order for sitename information when the resolver setup statement NOCOMMONSEARCH is specified (or left to default), and either the:

• getaddrinfo API is attempting to locate an IPv4 address.
• gethostbyname, sethostent, gethostent, or endhostent API is invoked.

If the COMMONSEARCH statement is specified, see IPv6/common search order, where the resolver can use IPNODES to locate sitenames.

The resolver uses the IPv4-unique search order for sitename information unconditionally for getnetbyname API calls.

The IPv4-unique search order for sitename information is as follows. The search ends at the first file found:

1. The value of the environment variable X_SITE

   The value of the environment variable is the name of the MVS™ data set that contains the sitename information. This data set is created by the TSO MAKESITE command.

2. /etc/hosts
3. userid.HOSTS.SITEINFO

   userid is the user ID that is associated with the current security environment (address space or task/thread).

4. hlq.HOSTS.SITEINFO

   hlq represents the value of the DATASETPREFIX statement specified in the base resolver configuration file (if found); otherwise, hlq is TCPIP by default.