When hosting multiple web applications,WE have to consider to have a different host header or port.
The combination host header + port must be unique to ensure a fully functional and reachable system.
Example: intranet.abc.com on port 80 and extranet.abc.com on port 80 are ok. [ In this case we have different host headers ]
Also : intranet.abc.com on port 80 and intranet.abc.com on port 85 are ok. [ In this case we have different ports]
What if you already have a Web application created using Classic Mode Authentication or How to convert Web application from Classic Mode authentication to Claims based Authentication?
You can convert that web application from classic mode authentication to claims based authentication. However this can only be done using PowerShell and it’s an irreversible process. Follow PowerShell commands to convert the web application from Classic Mode Authentication to Claims based Authentication: