This parameter controls whether to check if an aliased URL exists. During the course of a crawl we may
detect a server as an alias of another e.g.
home.example.com is an alias of
If this parameter is set to true then we will use a HTTP HEAD request to check if the aliased URL is there before making a full request. If the aliased URL does not exist we will then revert to the original URL.
This results in extra HTTP requests so the default setting is false i.e. we do not normally run this check as it is usually not required.