While installing portal, you may find below error while providing hostname
EJPIC0067E: Portal requires fully-qualified hostname that is recognized by the DNS server.Enter hostname again.
You will find these instruction to say about
Enter the fully qualified host name for the server, for example: hostname.example.com. Do not use a local host or a loopback address.
To resolve this problem, make an entry of hostname in host file location under C:\WINDOWS\system32\drivers\etc
Open file called hosts and make an entry like
Now again try installing portal and provide www.extremeportal.com as hostname.
You should be able to proceed with your portal installation afterwards.