Seeing errors in the webagent.log:
[344/4808][Sun Jan 22 2017 13:53:25][CSmHttpPlugin.cpp:353][ERROR] Unable to resolve fully qualified host name. Exiting with HTTP 500 server error '00-0016'.
which caused the Web Agent to eventually have initialization errors.
The 00-0016 error is being reported because a request is being made using the IP Address instead of the FQDN, and the Agent is unable to resolve the IP to a FQDN.
If the Agent is unable to make connections, it can potentially reach its idle timeout and shut down, causing it to stop serving requests. If the Agent is then restarted, it could cause initialization errors if not properly restarted.
Web Agent 12.0SP3, 12.5, 12.52, 12.52SP1
Use the ForceFQHost parameter in the Web Agent ACO or localconfig.conf.
Set ForceFQHost = yes (default: no)
The ForceFQHost parameter ensures the use of fully qualified domain names.This parameter uses DNS services to force the appending of the cookie domain to the host name in a URL request via DNS services and not an Agent.
If the Web Agent receives a request that contains a partial URL, the Web Agent redirects the request back to the same destination resource specified in the original URI. The redirect request uses the fully qualified host name, which the Web Agent determines using the configured domain name system DNS services. Enforcing the use of fully qualified domain names together with the Agent s ability to resolve cookie domains based on incoming host headers helps SiteMinder manage sites that have many domains across a network.