UNC paths are not supported.

Net use X: //blah blah/blah (plus username/password if you need it)
Dir X: (redirect to a file if you want)
Net use X: /delete

To build on HT9's example, you can wrap the statement in a FOR command to query additional websites from a file.

First, you would create a file with a list of the websites you wanted to check. Save it as a .txt file. You would also need to download the PSexecTools and add to your path (C:\windows\system32).

Your command to run to check multiple sites might look like this: (Untested, probably needs some additional fixes)

"
FOR /F %%i in (C:\sites.txt) do PSEXEC //%%i DIR (path) >> (full logfile.txt)
"

If you can substitute the FTP site for the server name, that would help. If you have Powershell available, this can be done easier and quicker.

This will run through a text file holding the name of the server or FTP path, connect to the machine locally, export the info to a log file (which can be local or remote) and move on to the next until the end of the file (EOF).