The resolver uses the IPv4-unique search order for address information when the resolver setup statement NOCOMMONSEARCH is specified (or left to default), and either the getnameinfo API is attempting to resolve an IPv4 address or the gethostbyaddr or GetHostString API is invoked. If the COMMONSEARCH statement is specified, see IPv6/common search order, where the resolver can use IPNODES to locate IPv4 and IPv6 addresses.
The resolver uses the IPv4-unique search order for address information unconditionally for the setnetent, getnetent, endnetent, or getnetbyaddr APIs.
The IPv4-unique search order for address information is as follows. The search ends at the first file found:
userid is the user ID that is associated with the current security environment (address space or task/thread).
jobname is the name specified on the JOB JCL statement for batch jobs or the procedure name for a started procedure.
hlq represents the value of the DATASETPREFIX statement specified in the base resolver configuration file (if found); otherwise, hlq is TCPIP by default.