How do you check if a web application extension already exist

Question

I can create a new web application extension using New-SPWebApplicationExtension but if it already exist I get an error with the message "The IIS Web Site you have selected is in use by SharePoint. You must select another port or hostname.".

I tried using Get-SPWebApplication but it does not return the extensions. I know I could catch the thrown exception and react on it but I wonder if there is a more cleaver way, e.g. Get-SPWebApplicationExtension that I can use to check if it already exist?

Answer 1

You have to use the Get-SPAlternateURL, it will return url from all zone then you will be know if one you are requesting being used or not

The Get-SPAlternateURL cmdlet returns all alternate URLs that match the scope given by either the optional Identity parameter or by a combination of the optional WebApplication, Zone, or Resource parameters. Each criterion that is added narrows the scope. If no criteria are specified then all alternate URLs are returned.

https://technet.microsoft.com/en-us/library/ff607923.aspx