Preparing an FQDN
AM requires that you provide an FQDN when you configure it. Before you set up AM, be sure that your system has an FQDN, such as openam.example.com. For evaluation purposes, you can give your system an alias using the /etc/hosts file on UNIX systems or %SystemRoot%\system32\drivers\etc\hosts on Windows. For production deployments, make sure the FQDN is properly assigned using DNS.
Do not use the hostname localhost for AM, not even for testing purposes. AM relies on browser cookies, which are returned based on the domain name. You can set the cookie domain name value to an empty string for host-only cookies or to any non-top level domain. For example, if you install AM and use openam.example.com as the host, you can set the cookie domain name as example.com.
Important
Do not configure a top-level domain as your cookie domain as browsers will reject them.
Top-level domains are browser-specific. Some browsers, like Firefox, also consider special domains like Amazon's web service (for example, ap-southeast-2.compute.amazonaws.com) to be a top-level domain.
Check the effective top-level domain list at https://publicsuffix.org/list/effective_tld_names.dat to ensure that you do not set your cookie to a domain in the list.